Flow sensors have diverse applications in the field of biomedical engineering and also in industries.
Micromachining of flow sensors has accomplished a new goal when it comes to miniaturization. Due to the
scaling in dimensions, power consumption, mass cost, sensitivity and integration with other modules such
as wireless telemetry has improvised to a great extent. Thermal flow sensors find wide applications in
biomedical such as in hydrocephalus shunts and drug delivery systems. Infrared thermal sensing is used for
preclinical diagnosis of breast cancer, for identifying various neurological disorders and for monitoring
various muscular movements. In this paper, various modes of thermal flow sensing and transduction
methods with respect to different biomedical applications are discussed. Thermal flow sensing is given
prime focus because of the simplicity in the design. Finally, a comparison of flow sensing technologies is
also presented.
Wireless Body Area Networks for Healthcare: A Surveyijasuc
Wireless body area networks (WBANs) are emerging as important networks, applicable in various
fields. This paper surveys the WBANs that are designed for applications in healthcare. We present a
comprehensive survey consisting of stand-alone sections focusing on important aspects of WBANs. We
examine the following: monitoring and sensing, power efficient protocols, system architectures, routing
and security. We conclude by discussing some open research issues, their potential solutions and future
trends.
Wireless Body Area Networks for Healthcare: A Surveyijasuc
Wireless body area networks (WBANs) are emerging as important networks, applicable in various
fields. This paper surveys the WBANs that are designed for applications in healthcare. We present a
comprehensive survey consisting of stand-alone sections focusing on important aspects of WBANs. We
examine the following: monitoring and sensing, power efficient protocols, system architectures, routing
and security. We conclude by discussing some open research issues, their potential solutions and future
trends.
You can learn about Function of Respiratoray System, Types of Respiration Rate Measurement Methods, Displacement Method, Thermistor Method, Impedance Pneumography, CO2 Method, Apnoea Detector, Block Diagram of Apnoea Detecto
Fundamentals of Thermal Mass Flow MeasurementSwanson Flo
“Why do we need to measure in mass flow? What is the difference between ACFM and SCFM? Why are pressure and temperature correction not required when measuring with a thermal mass flow meter? What is the thermal mass flow measurement theory? What are common applications to use thermal mass flow meters?” The white paper below attempts to explain these questions and more.
Unit-3 Instrumentation and control in mechanical engineering and other basic subject which contain instruments and their working under the syllabus of RGPV UNIVERSITY Bhopal.
Mechanical sensors and its working principles are discussed. The modern applications of the mechanical transducers or converters are also discussed. Motion, displacement, force, pressure, strain and many more concepts are discussed related mechanical sensors.
EXPERIMENTAL ANALYSIS OF HEAT TRANSFER AND FLUID FLOW IN MICRO-CHANNEL HEAT SINKijmech
In this paper heat transfer in single phase through micro-channels was studied. The validation of classical correlations of conventional channels to micro-channels is explored. It is found that classical approach is in good agreement with the experimental results of heat transfer in micro-channels .The material used for micro-channel heat sink (MCHS) is copper, experiments were conducted using water as cooling agent in
this study. Micro-channels are made with the help of EDM machine on the upper surface of MCHS. Variation of heat transfer rates, effect of friction factor, effect of pressure drop and variation in temperature distribution is investigated in this study. It is observed in the study that with decrease in
velocity flow friction also decreases.
Detection Methods:
There are five types of detection methods which are as:
Catalytic oxidation detectors
Electrochemical detectors
Optical detectors
Electrical conductivity (semiconductors) detectors
Chemical adsorbents detectors.
various types of temperature measuring instrument
1.expansion types
i)bimetallic strips
ii)liquid in gas
2.based on electric resistivity
i)thermocouple
ii)thermistors(most sensitivity)
3.pyrometers
i)mirror types
ii)optical
iii)photon types(not exact names:-based on collection of photon)
and one interesting term include in pyrometers is THERMOPILE:A large number of themocouple connected in series.Hopes so you all will enjoy
A Smart Flow Measurement System Adaptive to Different Variation Using Ultraso...Sheikh R Manihar Ahmed
This Paper Explain the Design of a Smart Flow measurement Technique using Ultrasonic Flow Meter for custody transfer quality. The objective of the work are; (i) to extend the linearity range of measurement to 100% of the input range, (ii) to make the measurement system adaptive to variations in pipe diameter, liquid density, and liquid temperature. An Accurate flow measurement is an essential requirement both from qualitative and economic points of view. Among the non contact type of flow measurement, ultrasonic flow measurement is widely used to measure flow, because of its advantage like high resolution and less interference of noise on output. However, non linear characteristics of Ultrasonic flow meters have restricted its use. An optimal Computational Logic is considered by comparing various schemes and algorithms based on minimization of Mean Square Error and Regression close to one. The output of ultrasonic flow meter is frequency. It is converted to voltage by using a frequency to voltage converter. An optimal Computational logic block is added in cascade to frequency to voltage converter. This arrangement helps to linearise the overall system for 100% of full scale and makes it adaptive to variations in pipe diameter, liquid density, and liquid temperature. Since the proposed Smart flow measurement technique produces output which is adaptive to variations in pipe diameter, liquid density, and liquid temperature, the present technique avoids the requirement of repeated calibration every time there is change in liquid, and/or pipe diameter, and/or liquid temperature. The results show that proposed measurement technique achieves the objectives quite satisfactorily.
Smart nanotechnology materials have been recently utilized in sensing applications. Carbon
nanotube (CNT) based SoC sensor systems have potential applications in various fields,
including medical, energy, consumer electronics, computers, and HVAC (heating, ventilation,
and air conditioning) among others. In this study, a nanotechnology multisensory system was
designed and simulated using Labview Software. The mathematical models were developed for
sensing three physical quantities: temperature, gas, and pressure. Four CNT groups on a chip
(two for gas sensor, one for temperature, and a fourth one for pressure) were utilized in order to
perform sensing multiple parameters. The proposed fabrication processes and the materials
used were chosen to avoid the interference of these parameters on each other when detecting
one of them. The simulation results were translated into analog voltage from Labview software,
transmitted via Bluetooth network, and received on desktop computers within the vicinity of the
sensor system. The mathematical models and simulation results showed as high as 95%
accuracy in measuring temperature, and the 5% error was caused from the interference of the surrounding gas. Within 7% change in pressure was impacted by both temperature and gas interference.
You can learn about Function of Respiratoray System, Types of Respiration Rate Measurement Methods, Displacement Method, Thermistor Method, Impedance Pneumography, CO2 Method, Apnoea Detector, Block Diagram of Apnoea Detecto
Fundamentals of Thermal Mass Flow MeasurementSwanson Flo
“Why do we need to measure in mass flow? What is the difference between ACFM and SCFM? Why are pressure and temperature correction not required when measuring with a thermal mass flow meter? What is the thermal mass flow measurement theory? What are common applications to use thermal mass flow meters?” The white paper below attempts to explain these questions and more.
Unit-3 Instrumentation and control in mechanical engineering and other basic subject which contain instruments and their working under the syllabus of RGPV UNIVERSITY Bhopal.
Mechanical sensors and its working principles are discussed. The modern applications of the mechanical transducers or converters are also discussed. Motion, displacement, force, pressure, strain and many more concepts are discussed related mechanical sensors.
EXPERIMENTAL ANALYSIS OF HEAT TRANSFER AND FLUID FLOW IN MICRO-CHANNEL HEAT SINKijmech
In this paper heat transfer in single phase through micro-channels was studied. The validation of classical correlations of conventional channels to micro-channels is explored. It is found that classical approach is in good agreement with the experimental results of heat transfer in micro-channels .The material used for micro-channel heat sink (MCHS) is copper, experiments were conducted using water as cooling agent in
this study. Micro-channels are made with the help of EDM machine on the upper surface of MCHS. Variation of heat transfer rates, effect of friction factor, effect of pressure drop and variation in temperature distribution is investigated in this study. It is observed in the study that with decrease in
velocity flow friction also decreases.
Detection Methods:
There are five types of detection methods which are as:
Catalytic oxidation detectors
Electrochemical detectors
Optical detectors
Electrical conductivity (semiconductors) detectors
Chemical adsorbents detectors.
various types of temperature measuring instrument
1.expansion types
i)bimetallic strips
ii)liquid in gas
2.based on electric resistivity
i)thermocouple
ii)thermistors(most sensitivity)
3.pyrometers
i)mirror types
ii)optical
iii)photon types(not exact names:-based on collection of photon)
and one interesting term include in pyrometers is THERMOPILE:A large number of themocouple connected in series.Hopes so you all will enjoy
A Smart Flow Measurement System Adaptive to Different Variation Using Ultraso...Sheikh R Manihar Ahmed
This Paper Explain the Design of a Smart Flow measurement Technique using Ultrasonic Flow Meter for custody transfer quality. The objective of the work are; (i) to extend the linearity range of measurement to 100% of the input range, (ii) to make the measurement system adaptive to variations in pipe diameter, liquid density, and liquid temperature. An Accurate flow measurement is an essential requirement both from qualitative and economic points of view. Among the non contact type of flow measurement, ultrasonic flow measurement is widely used to measure flow, because of its advantage like high resolution and less interference of noise on output. However, non linear characteristics of Ultrasonic flow meters have restricted its use. An optimal Computational Logic is considered by comparing various schemes and algorithms based on minimization of Mean Square Error and Regression close to one. The output of ultrasonic flow meter is frequency. It is converted to voltage by using a frequency to voltage converter. An optimal Computational logic block is added in cascade to frequency to voltage converter. This arrangement helps to linearise the overall system for 100% of full scale and makes it adaptive to variations in pipe diameter, liquid density, and liquid temperature. Since the proposed Smart flow measurement technique produces output which is adaptive to variations in pipe diameter, liquid density, and liquid temperature, the present technique avoids the requirement of repeated calibration every time there is change in liquid, and/or pipe diameter, and/or liquid temperature. The results show that proposed measurement technique achieves the objectives quite satisfactorily.
Smart nanotechnology materials have been recently utilized in sensing applications. Carbon
nanotube (CNT) based SoC sensor systems have potential applications in various fields,
including medical, energy, consumer electronics, computers, and HVAC (heating, ventilation,
and air conditioning) among others. In this study, a nanotechnology multisensory system was
designed and simulated using Labview Software. The mathematical models were developed for
sensing three physical quantities: temperature, gas, and pressure. Four CNT groups on a chip
(two for gas sensor, one for temperature, and a fourth one for pressure) were utilized in order to
perform sensing multiple parameters. The proposed fabrication processes and the materials
used were chosen to avoid the interference of these parameters on each other when detecting
one of them. The simulation results were translated into analog voltage from Labview software,
transmitted via Bluetooth network, and received on desktop computers within the vicinity of the
sensor system. The mathematical models and simulation results showed as high as 95%
accuracy in measuring temperature, and the 5% error was caused from the interference of the surrounding gas. Within 7% change in pressure was impacted by both temperature and gas interference.
Hydropower dam stress / strain & reinforcement measurement using ultrasonicsFrank-Michael Jäger
The system is based ultrasonic technology. With the highly accurate measurement of the running time (TOF) and the temperature with a sensor. With this technology, all parameters Stress, Strain, Load, Lenght and Elongation can be measured.
The resolution is in the ps range. The standard deviation is 35 ps.
The data are available in real time.
All sensors have the same electronics and can be exchanged for the servive.
The sensors have fixed cable RJ45 CAT6 PUR (operating temperature -40 ° C to + 80 ° C) with detachable connection for electronics with RS485 bus.
Each sensor has its own electronics with 12 bit temperature measurement. Each sensor can be addressed for the RS484 bus.
The power supply is 24 V (12 .... 30 V) DC.
The temperature range is - 40 ° C to + 80 ° C. A data logger with SD card can be delivered to the system. The recording rate
(E.g. every hour) is selected. About a USB interface, the data can be retrieved for further processing.
Standard 32 participants on the bus RS485. As an option is an extension to
256 participants possible.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Wind turbine foundation stress/strain & bolt measurement using ultrasonicsFrank-Michael Jäger
Each sensor has an own temperature sensor and a sensor ID in the ROM without own electronics for the measurement of the TOF.
The sensor cable is connected to a 16 -channel multiplexer. Each multiplexer includes electronics for measuring the TOF.
Each multiplexer has its own electronics unit in die-cast aluminum housing.
The data output is a digital output RS485.
Sensor ID, channel number, temperature 12 Bit, TOF in ps resolution.
The data is stored in a data logger on SD card.
The data can be read via USB.
On the RS485 bus more arbitrary devices can be connected.
The real-time data can with a computer program in any physical units, such as stress, strain, load or elongation be converted .
Implementation of Industrial Boiler Monitoring System with GSMSivasankarK11
The working of the boiler is monitored by means of their parameters. The parameters are the key of the proper functioning of the boiler. The steam produced in the boiler is used for various industrial applications. The application vary from the industrial purposes which may be for the power generation. Here the steam ids used for the testing of valves. The parameters of the boiler like temperature, pressure, pH and flow level are monitored. The parameters thus monitored are sent through the GSM (Global system for mobile Communication) to the control room of the industry.
Brief description: wind turbine foundation stress measurementFrank-Michael Jäger
System for measuring the stress/tension in the concrete foundation
of wind turbines
Delivery of a system for measurement of compressive stress and stress / strain or tensile stress in concrete for foundations of wind turbines.
Technical implementation in accordance with the system.
The foundation is a data logger for 32 channels RS485, sensors for compressive stress and tensile stress sensors are supplied.
Each sensor has an own temperature sensor and a sensor ID in the ROM without own electronics for the measurement of the TOF.
The sensor cable is connected to a 16 -channel multiplexer. Each multiplexer includes electronics for measuring the TOF.
Each multiplexer has its own electronics unit in die-cast aluminum housing.
The data output is a digital output RS485.
Sensor ID, channel number, temperature 12 Bit, TOF in ps resolution.
The data is stored in a data logger on SD card.
The data can be read via USB.
On the RS485 bus more arbitrary devices can be connected.
The real-time data can with a computer program in any physical units, such as stress, strain, load or elongation be converted .
GraphSummit Singapore | The Future of Agility: Supercharging Digital Transfor...Neo4j
Leonard Jayamohan, Partner & Generative AI Lead, Deloitte
This keynote will reveal how Deloitte leverages Neo4j’s graph power for groundbreaking digital twin solutions, achieving a staggering 100x performance boost. Discover the essential role knowledge graphs play in successful generative AI implementations. Plus, get an exclusive look at an innovative Neo4j + Generative AI solution Deloitte is developing in-house.
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
In this second installment of our Essentials of Automations webinar series, we’ll explore the landscape of triggers and actions, guiding you through the nuances of authoring and adapting workspaces for seamless automations. Gain an understanding of the full spectrum of triggers and actions available in FME, empowering you to enhance your workspaces for efficient automation.
We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
Goodbye Windows 11: Make Way for Nitrux Linux 3.5.0!SOFTTECHHUB
As the digital landscape continually evolves, operating systems play a critical role in shaping user experiences and productivity. The launch of Nitrux Linux 3.5.0 marks a significant milestone, offering a robust alternative to traditional systems such as Windows 11. This article delves into the essence of Nitrux Linux 3.5.0, exploring its unique features, advantages, and how it stands as a compelling choice for both casual users and tech enthusiasts.
Unlocking Productivity: Leveraging the Potential of Copilot in Microsoft 365, a presentation by Christoforos Vlachos, Senior Solutions Manager – Modern Workplace, Uni Systems
Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Sudheer Mechineni, Head of Application Frameworks, Standard Chartered Bank
Discover how Standard Chartered Bank harnessed the power of Neo4j to transform complex data access challenges into a dynamic, scalable graph database solution. This keynote will cover their journey from initial adoption to deploying a fully automated, enterprise-grade causal cluster, highlighting key strategies for modelling organisational changes and ensuring robust disaster recovery. Learn how these innovations have not only enhanced Standard Chartered Bank’s data infrastructure but also positioned them as pioneers in the banking sector’s adoption of graph technology.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
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GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Maruthi Prithivirajan, Head of ASEAN & IN Solution Architecture, Neo4j
Get an inside look at the latest Neo4j innovations that enable relationship-driven intelligence at scale. Learn more about the newest cloud integrations and product enhancements that make Neo4j an essential choice for developers building apps with interconnected data and generative AI.
zkStudyClub - Reef: Fast Succinct Non-Interactive Zero-Knowledge Regex ProofsAlex Pruden
This paper presents Reef, a system for generating publicly verifiable succinct non-interactive zero-knowledge proofs that a committed document matches or does not match a regular expression. We describe applications such as proving the strength of passwords, the provenance of email despite redactions, the validity of oblivious DNS queries, and the existence of mutations in DNA. Reef supports the Perl Compatible Regular Expression syntax, including wildcards, alternation, ranges, capture groups, Kleene star, negations, and lookarounds. Reef introduces a new type of automata, Skipping Alternating Finite Automata (SAFA), that skips irrelevant parts of a document when producing proofs without undermining soundness, and instantiates SAFA with a lookup argument. Our experimental evaluation confirms that Reef can generate proofs for documents with 32M characters; the proofs are small and cheap to verify (under a second).
Paper: https://eprint.iacr.org/2023/1886
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Discover how Changi Airport Group (CAG) leverages graph technologies and generative AI to revolutionize their search capabilities. This session delves into the unique search needs of CAG’s diverse passengers and customers, showcasing how graph data structures enhance the accuracy and relevance of AI-generated search results, mitigating the risk of “hallucinations” and improving the overall customer journey.
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GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
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The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
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Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...
A COMPARATIVE ANALYSIS OF THERMAL FLOW SENSING IN BIOMEDICAL APPLICATIONS
1. International Journal of Biomedical Engineering and Science (IJBES), Vol. 3, No. 3, July 2016
DOI: 10.5121/ijbes.2016.3301 1
A COMPARATIVE ANALYSIS OF THERMAL FLOW
SENSING IN BIOMEDICAL APPLICATIONS
Baseerat Khan, Suhaib Ahmed and Vipan Kakkar
Department of Electronics and Communication Engineering, Shri Mata Vaishno Devi
University, Katra, India
ABSTRACT
Flow sensors have diverse applications in the field of biomedical engineering and also in industries.
Micromachining of flow sensors has accomplished a new goal when it comes to miniaturization. Due to the
scaling in dimensions, power consumption, mass cost, sensitivity and integration with other modules such
as wireless telemetry has improvised to a great extent. Thermal flow sensors find wide applications in
biomedical such as in hydrocephalus shunts and drug delivery systems. Infrared thermal sensing is used for
preclinical diagnosis of breast cancer, for identifying various neurological disorders and for monitoring
various muscular movements. In this paper, various modes of thermal flow sensing and transduction
methods with respect to different biomedical applications are discussed. Thermal flow sensing is given
prime focus because of the simplicity in the design. Finally, a comparison of flow sensing technologies is
also presented.
KEYWORDS
Biomedical, Flow Sensors, MEMS, Thermal Flow, Transduction
1. INTRODUCTION
Flow sensors have a great utility in industrial, biomedical and research fields for monitoring and
control operations. Flow sensors that are based on micromachining add aflavor to technologies
such as valves, fluidic channels, heater elements for creating a complete micro analysis system
e.g.; implantable micro-pumps can be used to deliver drugs without the need for inserting needle
in human skin[2].
Fluid flow can be measured by different methods and can be categorized at macro-scale and
micro-scale level. Mechanical flow-meters such as venture-meter, positive displacement meters
and orifice are used to measure flow rate at macro levels and are extensively used for industrial
purpose. Because of their moving parts, interference with the fluid flow, and difficulty in
fabrication, these flow sensors can’t be used for micro scale applications such as in biomedical.
At micro level, micromachined flow sensors are without any moving parts and hence are easy for
fabrication process and also simplify the operational requirements. As a result, great interest is
being developed in the MEMS community for fabrication of micro sensors. Micromachined flow
sensors are used to check the oscillation of the fluid in fluidic micro-channels [1].This allows
monitoring the flow behaviour in real time and avoiding misdiagnosis. The flow sensors can also
be categorized as electronic sensors based on operation principles. This includes thermal and
ultrasonic sensors.
Thermal flow sensors measure the flow rate of a fluid by measuring the changes in thermal
phenomenon by heat transfer such as conduction, convection or radiation. The signal can be
transduced into the electrical signal (voltage) to measure the sensor response to the flow. The
2. International Journal of Biomedical Engineering and Science (IJBES), Vol. 3, No. 3, July 2016
2
flow sensors that are of micro range are gaining prime importance because of lower power
consumption, high sensitivity to flow rates and can easily be operated in different modes.
Moreover, these sensors can measure the thermal properties of fluid (e.g. blood or CSF) such as
conductivity or diffusivity [3].
Thermal flow sensors are thermally isolated so that heat loss only due to convective cooling
should occur. Losses due to substrate and other metallic contacts degrade the sensor performance.
The sensitivity and power consumption can be optimized by varying the shape and position of the
sensor. Also, a suitable material should be chosen for the design of flow sensor.
Ultrasonic sensors measure the flow such as blood flow by using the propagating principle of
ultrasound signal in tissue. The ultrasound frequencies are in the range of above 20 kHz.These
sensors find wide applications in medicine such as in imaging. Doppler sensors and time of flight
sensors are sub-categories of ultrasonic sensors. Doppler sensors measure the flow velocity by
measuring the shift in frequency, commonly known as Doppler shift between the transmitted and
received signal. The equation for determining velocity is:
ܸௗ =
݂ܿௗ
2݂ܿߠݏ
Where,
݂ௗ is the Doppler frequency,
݂ is incident frequency, and ߠ is the angle of placement of sensor with respect to vessel.
Time of flight sensors measure the flow by measuring the difference between the transit times.
An implantable time of flight sensor using electrochemical impedance was developed for in-vivo
monitoring within shunts for hydrocephalic patients [5].
2. MODES OF THERMAL SENSING
Various modes of flow sensing are: Calorimetric, anemometric and thermal time of flight are the
three modes of flow sensing:
2.1. Anemometric sensors
It operates by transferring heat from a locally heated element such as micro-heater to the fluid
flowing around it. Hot-film and hot-wire sensors operate using the same physical principle. Hot
film uses a resistive thin film having different values of resistance depending upon the material
used whereas, hot wire uses simply a metal wire. The rate at which convective heat loss occurs
can be measured and correlated to flow velocity. Thermal properties, heater temperature and
velocity of the fluid dictates the amount of heat transferred to the fluid. Figure 1 gives an
illustration of anemometric sensing.
Figure 1. Anemometric Sensor
3. International Journal of Biomedical Engineering an
The material chosen for heating element should have high thermal coefficient of resistance, as
sensitivity of the sensor is proportional to material’s coefficient of resistance. Nichrome, platinum
are the preferable choices as they are biocompatible and ar
applications such as in medical tubing and implantable devices. Also, platinum is resistant to
corrosion and compatible with micromachining techniques.
Anemometric sensors operate in either constant temperature mode or
constant temperature mode, the temperature is held constant by controlling the power dissipated
by the sensor. With the increase in fluid flow rate, the thermal conductance of the element
increases and more heat is dissipated. Howev
constant by applying a constant current bias to the heating element and changes in resistance or
voltage are correlated to the flow rate.Constant temperature mode is preferred over constant
power because of the better sensitivity and frequency response [3].
2.2. Calorimetric flow sensor
Calorimetric sensing requires a thermal sensor placed upstream and downstream to the heating
element. The variation in upstream and downstream temperature due to the flow gives
measure of fluid velocity. The working of a calorimetric sensor is illustrated in figure 2.
Figure 2.
Greater the flow rate, greater will be the variation between the upstream and downstream
temperatures.
3.3. Thermal time of flight
In this mode of sensing, a thermal pulse is generated by a hot wire and injected into the fluid
stream. The downstream sensor detects the heat pulse which is carried away from source by the
fluid flow. The time it takes for an input sig
used to determine the flow rate. Thermal conductivity, flow velocity and distance between
heating element and sensing element are certain factors which have a great influence on transit
time. Figure 3 gives an insight into working of time of flight sensor.
Figure 3.
International Journal of Biomedical Engineering and Science (IJBES), Vol. 3, No. 3, Ju
The material chosen for heating element should have high thermal coefficient of resistance, as
sensitivity of the sensor is proportional to material’s coefficient of resistance. Nichrome, platinum
are the preferable choices as they are biocompatible and are more commonly used in biomedical
applications such as in medical tubing and implantable devices. Also, platinum is resistant to
corrosion and compatible with micromachining techniques.
Anemometric sensors operate in either constant temperature mode or constant power mode. In
constant temperature mode, the temperature is held constant by controlling the power dissipated
by the sensor. With the increase in fluid flow rate, the thermal conductance of the element
increases and more heat is dissipated. However, in constant power mode, the power remains
constant by applying a constant current bias to the heating element and changes in resistance or
voltage are correlated to the flow rate.Constant temperature mode is preferred over constant
better sensitivity and frequency response [3].
2. Calorimetric flow sensor
Calorimetric sensing requires a thermal sensor placed upstream and downstream to the heating
element. The variation in upstream and downstream temperature due to the flow gives
measure of fluid velocity. The working of a calorimetric sensor is illustrated in figure 2.
Figure 2. Calorimetric Sensor [17]
Greater the flow rate, greater will be the variation between the upstream and downstream
In this mode of sensing, a thermal pulse is generated by a hot wire and injected into the fluid
stream. The downstream sensor detects the heat pulse which is carried away from source by the
fluid flow. The time it takes for an input signal from generation to detection (transit time) can be
used to determine the flow rate. Thermal conductivity, flow velocity and distance between
heating element and sensing element are certain factors which have a great influence on transit
gives an insight into working of time of flight sensor.
Figure 3. Thermal Time of Flight [17]
uly 2016
3
The material chosen for heating element should have high thermal coefficient of resistance, as
sensitivity of the sensor is proportional to material’s coefficient of resistance. Nichrome, platinum
e more commonly used in biomedical
applications such as in medical tubing and implantable devices. Also, platinum is resistant to
constant power mode. In
constant temperature mode, the temperature is held constant by controlling the power dissipated
by the sensor. With the increase in fluid flow rate, the thermal conductance of the element
er, in constant power mode, the power remains
constant by applying a constant current bias to the heating element and changes in resistance or
voltage are correlated to the flow rate.Constant temperature mode is preferred over constant
Calorimetric sensing requires a thermal sensor placed upstream and downstream to the heating
element. The variation in upstream and downstream temperature due to the flow gives an indirect
measure of fluid velocity. The working of a calorimetric sensor is illustrated in figure 2.
Greater the flow rate, greater will be the variation between the upstream and downstream
In this mode of sensing, a thermal pulse is generated by a hot wire and injected into the fluid
stream. The downstream sensor detects the heat pulse which is carried away from source by the
nal from generation to detection (transit time) can be
used to determine the flow rate. Thermal conductivity, flow velocity and distance between
heating element and sensing element are certain factors which have a great influence on transit
4. International Journal of Biomedical Engineering an
3. DIFFERENT TRANSDUCTION
Thermal flow sensors use thermoelectric, thermo
mechanism.Thermoresistive sensors simply use a resistor to which a certain potential is applied at
the terminals. When the fluid flows over the sensor, convective heat loss occurs and as such there
is a drop in temperature. Decrease in temperature causes a substantial dec
which causes change in voltage or current. This change can be calibrated to the fluid flow. These
sensors are by far used widely because of its easy fabrication and operability.
Thermoelectric sensors use a heating element in conjunct
thermocouples are connected in series, they form thermopiles. The output voltage of a thermopile
due to temperature changes is the summation of individual output voltages of series connected
thermocouple. The output voltage
Where,
ߙis seebeck coefficient of material
ߙ is seebeck coefficient of material
ܶ is hot junction temperature
ܶ is the cold junction temperature.
However, these are not much used because of the less conventional materials required for its
fabrication, which makes it complicated. Also with the increase in number of thermocouples, the
performance of sensor degrades because
are the commonly used materials for thermoelectric transduction.
Surface acoustic wave flow sensors and cantilevers sense the changes in the resonant frequency
of the substrate in response to the st
developed using a quartz material. ST
temperature stability. The test results showed a change of 4.24 degree/kpa in terms of pressure
and a phase change of 1 degree for 11.8 ml/min change in flow rate [6].From fabrication point of
view SAW sensors use conventionalpiezoelectric materials such as ST
consumption, easy operability and compatibility with wireless module are certain f
SAW sensors. However, it has limited compatibility with the CMOS devices
certain potential constraints.
International Journal of Biomedical Engineering and Science (IJBES), Vol. 3, No. 3, Ju
RANSDUCTION PRINCIPLES
sors use thermoelectric, thermoresistive or acoustic principles for transducing
resistive sensors simply use a resistor to which a certain potential is applied at
the terminals. When the fluid flows over the sensor, convective heat loss occurs and as such there
is a drop in temperature. Decrease in temperature causes a substantial decrease in resistance,
which causes change in voltage or current. This change can be calibrated to the fluid flow. These
sensors are by far used widely because of its easy fabrication and operability.
Thermoelectric sensors use a heating element in conjunction with the thermocouples. When
thermocouples are connected in series, they form thermopiles. The output voltage of a thermopile
due to temperature changes is the summation of individual output voltages of series connected
thermocouple. The output voltage is determined from the equation given below:
ܸ=ሺߙ െ ߙሻሺܶ െ ܶ)
seebeck coefficient of material ‘a’;
seebeck coefficient of material ‘b’;
ot junction temperature, and
cold junction temperature.
However, these are not much used because of the less conventional materials required for its
fabrication, which makes it complicated. Also with the increase in number of thermocouples, the
performance of sensor degrades because of the increase in Johnson noise. Polysilicon and metals
are the commonly used materials for thermoelectric transduction.
Surface acoustic wave flow sensors and cantilevers sense the changes in the resonant frequency
of the substrate in response to the stresses applied to the material. A novel wave flow sensor was
developed using a quartz material. ST-X quartz material was chosen because of excellent
temperature stability. The test results showed a change of 4.24 degree/kpa in terms of pressure
change of 1 degree for 11.8 ml/min change in flow rate [6].From fabrication point of
view SAW sensors use conventionalpiezoelectric materials such as ST-X quartz. Low power
consumption, easy operability and compatibility with wireless module are certain f
SAW sensors. However, it has limited compatibility with the CMOS devices and
Figure 4. SAW port structure [6]
uly 2016
4
principles for transducing
resistive sensors simply use a resistor to which a certain potential is applied at
the terminals. When the fluid flows over the sensor, convective heat loss occurs and as such there
rease in resistance,
which causes change in voltage or current. This change can be calibrated to the fluid flow. These
ion with the thermocouples. When
thermocouples are connected in series, they form thermopiles. The output voltage of a thermopile
due to temperature changes is the summation of individual output voltages of series connected
However, these are not much used because of the less conventional materials required for its
fabrication, which makes it complicated. Also with the increase in number of thermocouples, the
of the increase in Johnson noise. Polysilicon and metals
Surface acoustic wave flow sensors and cantilevers sense the changes in the resonant frequency
resses applied to the material. A novel wave flow sensor was
X quartz material was chosen because of excellent
temperature stability. The test results showed a change of 4.24 degree/kpa in terms of pressure
change of 1 degree for 11.8 ml/min change in flow rate [6].From fabrication point of
X quartz. Low power
consumption, easy operability and compatibility with wireless module are certain features of
and also poses
5. International Journal of Biomedical Engineering an
4. APPLICATIONS OF MICRO
Mailly et al. [7] fabricated two platinum films which were developed as resistors on a substrate
.The resistors act as a temperature sensor and a heating element, respectively, to measure the fluid
rate. A silicon nitride layer is used as thermal isolation layer over the s
and electrical analysis of the model was done.A flexible sensor was mounted on a substrate of
parylene, which is a cross linked polymer. The sensor was placed in a conductive catheter and
used to measure the pulsatile blood flow in
Bailey et al. [9] fabricated a wire made up of platinum having dimensions 100 nm×
2µm×60µm.The frequency and spatial results were better in compariso
anemometers.Later on, carbon nanotubes were added to increase t
et al. [10] used finite element method software for developing a calorimetric flow meter. The flow
was measured by calculating the difference between the upstream and downstream temperature
around the heater element. The pro
database. The results were that greater the fluid velocity, greater will be the heat distribution
around the heater element. For bio
design variable and it should have less interference with the fluid profile [10] the results were
then compared with the actual experimental setup.
A flow sensor incorporated in a catheter was presented for real time cerebral blood flow
monitoring in certain region of interest
mode and employs four wire configurations for periodic heating and cooling mechanism. This
approach gives reliable results and ensures zero drift with MEMS based sensors. The results sh
that the sensor has a sensitivity of 0.973 mV/ml/100 g/min in the range from 0
[11].Further scope is multiple sensors can be incorporated in a catheter for neuro
monitoring.
Fig. 5: Smart Catheter flow sensor [11]
A novel flow sensor system was modeled using thermal time of flight principle. The system is
regarded as a linear time invariant system, comprising of temperature sensors and a hot wire.
Fluid velocity, fluid media and certain heat effects were measured using sig
and fall times and also by the thermo fluid measurement. Ecin et al. actually presented the
mathematical model with thermodynamic and fluid mechanical properties [12].
In [13], a parylene based micro flow sensor was designed and
impedance transduction technique. Three pair of electrodes were used, one for bubble generation
and other two for measurements. This
within shunts for hydrocephalic pa
used as a tracer, was obtained over the velocity of 0.83
rate was inversely proportional to time of flight.
A linearization bridge technique of p
the flow characteristic is non-linear. The system has been developed and fabricated and the
experimental results show linearity in flow characteristics. In this paper, an electric equivalen
the sensor has been designed.
International Journal of Biomedical Engineering and Science (IJBES), Vol. 3, No. 3, Ju
ICRO THERMAL MACHINED SENSORS
fabricated two platinum films which were developed as resistors on a substrate
.The resistors act as a temperature sensor and a heating element, respectively, to measure the fluid
rate. A silicon nitride layer is used as thermal isolation layer over the substrate [7].The thermal
and electrical analysis of the model was done.A flexible sensor was mounted on a substrate of
parylene, which is a cross linked polymer. The sensor was placed in a conductive catheter and
used to measure the pulsatile blood flow in arteries of rabbits [8].
fabricated a wire made up of platinum having dimensions 100 nm×
2µm×60µm.The frequency and spatial results were better in comparison to traditional
.Later on, carbon nanotubes were added to increase the sensitivity of a sensor.Neto
used finite element method software for developing a calorimetric flow meter. The flow
was measured by calculating the difference between the upstream and downstream temperature
around the heater element. The properties of the heater element were set from the material
database. The results were that greater the fluid velocity, greater will be the heat distribution
around the heater element. For bio-sensing, the height of the heater element is an important
ariable and it should have less interference with the fluid profile [10] the results were
then compared with the actual experimental setup.
A flow sensor incorporated in a catheter was presented for real time cerebral blood flow
on of interest in [11]. The sensor is operated in constant temperature
mode and employs four wire configurations for periodic heating and cooling mechanism. This
approach gives reliable results and ensures zero drift with MEMS based sensors. The results sh
that the sensor has a sensitivity of 0.973 mV/ml/100 g/min in the range from 0-160 ml/100 g/min
[11].Further scope is multiple sensors can be incorporated in a catheter for neuro
Fig. 5: Smart Catheter flow sensor [11]
flow sensor system was modeled using thermal time of flight principle. The system is
regarded as a linear time invariant system, comprising of temperature sensors and a hot wire.
Fluid velocity, fluid media and certain heat effects were measured using signal analysis of rise
and fall times and also by the thermo fluid measurement. Ecin et al. actually presented the
mathematical model with thermodynamic and fluid mechanical properties [12].
[13], a parylene based micro flow sensor was designed and fabricated using electrochemical
impedance transduction technique. Three pair of electrodes were used, one for bubble generation
and other two for measurements. This sensor was used for chronic in-vivo monitoring of fluid
within shunts for hydrocephalic patients. High precision measurement of micro-bubble, which is
used as a tracer, was obtained over the velocity of 0.83-83µm/sec. The results show that the flow
rate was inversely proportional to time of flight.
ization bridge technique of p-n junction anemometric sensor has been proposed
linear. The system has been developed and fabricated and the
experimental results show linearity in flow characteristics. In this paper, an electric equivalen
uly 2016
5
fabricated two platinum films which were developed as resistors on a substrate
.The resistors act as a temperature sensor and a heating element, respectively, to measure the fluid
ubstrate [7].The thermal
and electrical analysis of the model was done.A flexible sensor was mounted on a substrate of
parylene, which is a cross linked polymer. The sensor was placed in a conductive catheter and
fabricated a wire made up of platinum having dimensions 100 nm×
n to traditional
he sensitivity of a sensor.Neto
used finite element method software for developing a calorimetric flow meter. The flow
was measured by calculating the difference between the upstream and downstream temperature
perties of the heater element were set from the material
database. The results were that greater the fluid velocity, greater will be the heat distribution
sensing, the height of the heater element is an important
ariable and it should have less interference with the fluid profile [10] the results were
A flow sensor incorporated in a catheter was presented for real time cerebral blood flow
. The sensor is operated in constant temperature
mode and employs four wire configurations for periodic heating and cooling mechanism. This
approach gives reliable results and ensures zero drift with MEMS based sensors. The results show
160 ml/100 g/min
[11].Further scope is multiple sensors can be incorporated in a catheter for neuro-modal
flow sensor system was modeled using thermal time of flight principle. The system is
regarded as a linear time invariant system, comprising of temperature sensors and a hot wire.
nal analysis of rise
and fall times and also by the thermo fluid measurement. Ecin et al. actually presented the
fabricated using electrochemical
impedance transduction technique. Three pair of electrodes were used, one for bubble generation
vivo monitoring of fluid
bubble, which is
83µm/sec. The results show that the flow
ion anemometric sensor has been proposed in [14] as
linear. The system has been developed and fabricated and the
experimental results show linearity in flow characteristics. In this paper, an electric equivalent of
6. International Journal of Biomedical Engineering and Science (IJBES), Vol. 3, No. 3, July 2016
6
A MEMS based flexible flow sensor for online monitoring of body fluid such as blood was
proposed and integrated with catheter. A resistive heater element of varying geometries was
placed on a substrate of different materials and the velocity profile, temperature distribution of
fluid around the heater element was analyzed [15].
The development and fabrication of a thermal flow sensor, used for biological and chemical
applications has been discussed in [16]. Finite element software was used for the simulation and
the simulation showed a sensitivity of µv/µL/min with a resolution of 10µL/min. For an input
current of 40mA and heater width of 50µm, the temperature of the fluid increased by 5°C.The
results show that the sensor has suitable sensitivity with low interference in fluid flow.
5. PERFORMANCE COMPARISON OF THERMAL FLOW SENSORS
The advantages and the shortcomings/challenges of the various thermal flow sensors can be
summarized by Table 1.
Table 1. Comparison of different thermal flow sensors
Sensor Type Advantages Challenges
Calorimetric • Inherently sensitive to
mass flow
• Need for localized heat
Anemometric
• Mass flow is sensitive to
heat transfer
• Simple technique to use
• Better performance over
a wide range of flow
• Non-linearity in flow
Ultrasonic
• No-invasive in nature
• Can be used as a clamp
on transducer
• Requires precise and stable
alignment of beam on blood
vessel
• Slight deviations or
miscalculations can cause
erroneous results
• Traces or particles are
required to reflect the signal
The most important design parameter is that the substrate should have minimal thermal
conductivity so that large amount of heat is not dissipated to it. Polymers have minimal thermal
conductivity and are mostly used as substrate material and are also used for packaging. The
geometry of the heating element is also a very critical parameter as the sensitivity of a device
depends on the conductance, which in turn depends on the size and shape of the sensing element.
6. CONCLUSION
Micromachining of thermal flow sensors provides us with a platform for establishing new
methodologies. Different modes of transduction and diversity in materials can be used for wide
application range. Thermal sensing can be used for diagnosis and monitoring of fluid rates in
human body for timely intervention. A simple system controlling current through a resistive
element (hot-film or hot-wire) is preferential over other sensor systems. The output parameter
such as voltage can be correlated to the fluid velocity. Minimal power consumption, easy
operation and fabrication are some of the advantages that make thermal sensing an ultimate
choice.
7. International Journal of Biomedical Engineering and Science (IJBES), Vol. 3, No. 3, July 2016
7
REFERENCES
[1] N.T Nguyen. “Micro machined flow sensors-a review.” Flow Measurementand Instrumentation,
vol. 8,no.1, pp.7 – 16, 1997.
[2] Waldron, Matthew J., “Design, simulation, and fabrication of a flow sensor for an implantable
micro pump” (2009).Thesis, Rochester Institute of Technology.
[3] W.-KMeng, E.F.-C. “MEMS Technology and Devices for a Micro fluid Dosing System”. Ph.D.
Dissertation, California Institute of Technology, Pasadena, CA, USA, 2003, pp. 150.
[4] John G. Webster, “Medical Instrumentation-Application and Design”, John Wiley and Sons,
Singapore (2005).
[5] Yu, L.; Kim, B.J.; Meng, E., "An implantable time of flight flow sensor,” in Micro Electro
Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, pp.620-623, 18-
22 Jan. 2015.
[6] Yizhong Wang; Zheng Li; Lifeng Qin; Chyu, M.K.; Qing-Ming Wang, "Surface acoustic wave
flow sensor," in Frequency Control and the European Frequency and Time Forum (FCS), 2011
Joint Conference of the IEEE International , pp.1-4, 2-5 May 2011.
[7] Mailly, F., et al., "Anemometer with hot platinum thin film,” Sensors and Actuators, A: Physical,
vol.94,no.(1-2), pp.32-38,2001.
[8] Bailey, Sean CC, et al. "Turbulence measurements using a nanoscale thermal anemometry
probe." Journal of Fluid Mechanics 663 (2010): 160-179.
[9] Wu, S.; Lin, Q.; Yuen, Y.; Tai, Y.-C. “MEMS flow sensors for Nano-fluidic applications”. Sens.
Actuat. A .vol. 89, pp.152–158,2001.
[10] Barreto Neto, A.G.S.; Lima, A.M.N.; Moreira, C.S.; Neff, H., "Design and theoretical analysis of a
bidirectional calorimetric flow sensor," in Instrumentation and Measurement Technology
Conference (I2MTC) Proceedings, 2014 IEEE International,pp.542-545, 12-15 May 2014.
[11] Chunyan Li; Pei-Ming Wu; Zhizhen Wu; Ahn, C.H.; Hartings, J.A.; Narayan, R.K., "Smart
catheter flow sensor for continuous regional cerebral blood flow monitoring," in Sensors, 2011
IEEE, pp.1417-1420, 28-31 Oct. 2011.
[12] Ecin, O.; Zhao, R.; Hosticka, B.J.; Grabmaier, A., "Thermo-fluid dynamic Time-of-Flight flow
sensor system," in Sensors, 2012 IEEE, Taipei,pp.1-4, 28-31 Oct. 2012.
[13] Yu, L.; Kim, B.J.; Meng, E., "An implantable time of flight flow sensor," in Micro Electro
Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, Estoril,2015,pp.620-
623, 18-22 Jan. 2015.
[14] Bera, S.C.; Marick, S., "Study of a Simple Linearization Technique of p-n-Junction-Type
Anemometric Flow Sensor," in Instrumentation and Measurement, IEEE Transactions on , vol.61,
no.9, pp.2545-2552, Sept. 2012.
[15] Maji, D.; Das, S., "Simulation and feasibility study of flow sensor on flexible polymer for
healthcare application," in Point-of-Care Healthcare Technologies (PHT), 2013 IEEE, pp.132-
135, 16-18 Jan. 2013.
[16] Mielli, M.Z.; Carreno, M.N.P., "Thermal flow sensor integrated to PDMS-based microfluidic
systems," in Microelectronics Technology and Devices (SBMicro), 2013 Symposium on, pp.1-4, 2-
6 Sept. 2013.
[17] Jonathan T.W.Kuo,Lawrence Yu,Ellis Meng, “Micromachined thermal flow sensors-A
Review”,Micromachines,vol. 3,no.3, pp. 570-573,2012.
[18] Wu, S.; Lin, Q.; Yuen, Y.; Tai, Y.-C. “MEMS flow sensors for nano-fluidic applications”, Sens.
Actuat., vol.89, pp. 152–158,2001.
[19] Yu, H.; Ai, L.; Rouhanizadeh, M.; Patel, D.; Kim, E.S.; Hsiai, T.K. “Flexible polymer sensors
for in vivo intravascular shear stress analysis” J. Microelectromechanical Syst.,vol.17,pp.1178–
1186,2008.
[20] Meng, E.; Li, P.-Y.; Tai, Y.-C, “A biocompatible Parylene thermal flow sensing array,” Sens.
Actuat. A,vol. 144,pp. 18–28,2008