Cliff Tsai Portfolio_04272016 - HWSW

Portfolio in reverse chronological order Tsungchan Tsai (Cliff Tsai)
1
Hardware

2
Project 1 – Medical Device/Plasma Technology Development Project @ EP
Technologies LLC (2013-2014):
Rapid Inactivation of Bacterial Spores Using Plasma Activated Water:
Development, Species Identification and Sporicidal Mechanism
Project Feature: A new non-thermal plasma method to rapidly kill bacterial spores on dry surfaces
Required Skills: Plasma medicine, interaction of plasma with microbes, microbiology, plasma
chemistry, plasma engineering
Abstract: This work demonstrated that plasma activated water (PAW) can be used to achieve rapid
inactivation of C. difficile spores on dry hard surfaces as long as the powerful, short-lived aqueous
species can be produced in the vicinity of the spores. The experimental results showed that a higher
than 6 log reduction of C. difficile spores can be achieved within a 10 second exposure time. It was
found that the PAW treatments had a more rapid and efficacious sporicidal activity than the dry plasma
methods (both the direct DBD and the mini-plasmatron) likely due to the synergistic action of the
powerful, short-lived liquid-phase species (e.g., ONOOH) and the low pH. Spore coat and membrane
damage appeared to be the key sporicidal mechanism using activated droplets.
Accomplishment:
 An oral presentation was given in the 22nd
International Symposium on Plasma Chemistry
Society (ISPC 22) in Belgium
 A conference paper (ISPC 22 Proceedings) based on this work was published

3
Project 2 – Plasma Technology & Process Development Project @ Texas A&M
(2009-2012):
Polymer film deposition onto temperature-sensitive substrates in ambient air
conditions using a plasma jet
Project Feature: A new method/process to grow materials on living surfaces in open air conditions
using AP-PECVD
Required Skills: PECVD, plasma-material interaction, plasma chemistry, plasma engineering,
polymer engineering, FTIR, profilometer, XPS, AFM, SEM, optical emission spectroscopy (OES)
Abstract: A new system to deposit polymer films onto temperature-sensitive surfaces in open air
conditions by using an atmospheric non-thermal helium dielectric barrier discharge (DBD) plasma jet
was developed. Two distinct modes, which are diffuse mode and concentrated mode, were observed in
the plasma jet with the rising applied power. Methyl methacrylate (MMA) was employed as the
monomer for depositing PMMA films. The results showed that a high deposition rate (22 nm·sec−1
)
can be attained with a discharge power of 3.5 W and deposition temperature of 39 °C. In addition to
typical transparent PMMA films, opaque films with wrinkled microstructures can be obtained by using
the concentrated-mode plasma jet likely due to a buckling effect. High quality (RMS roughness is
0.4±0.1 nm) of the deposited transparent films was also demonstrated by SEM and AFM imaging
techniques. Similar functional groups were observed comparing pure PMMA and the films deposited
at different powers by using FTIR. XPS analysis showed that a higher power leads to higher C:O ratio
in the deposited films. Besides, the less retention of ester groups and the higher concentration of the
–CHn groups were observed with a higher plasma power. The MMA addition to the helium plasma jet
inhibited the generation of NO and OH excited species. By using this proposed polymer deposition
technique, rapid polymer film growth can be achieved on various types of temperature-sensitive
substrates (e.g., plastic, rubber, onion, and fingernail) with similar characteristic features to the
conventional polymer films.
PMMA Film
Bubbler
Finger (Floating electrode)
DBD jet
Powered
electrode
Accomplishment:
 A journal paper (Plasma Processes and Polymers, vol. 8, pp. 523 (2011)) based on this work
was published
 A patent based on this work was granted/issued

4
(2009-2012):
Metal film deposition onto temperature-sensitive substrates in ambient air
conditions using a plasma jet
Project Feature: A pioneer work which first demonstrated that copper films can be deposited in open
air conditions with an electrical conductivity close to that of bulk iron
Required Skills: PECVD, plasma-material interaction, plasma chemistry, plasma engineering, redox
reaction, electrical resistance measurement, profilometer, XPS, SEM, OES
Abstract: Deposition of metallic copper films were accomplished at ambient air conditions using a
helium DBD plasma jet with the addition of hydrogen (H2) and Cu(acac)2 vapor, which was sublimed
from its solid state at 90 °C. A change in the operation mode of the plasma jet was observed with the
rising applied power. Initially a diffuse mode was present at the low power. Higher power led to the
transition to a concentrated mode, in which a plasma channel with relatively high intensity was formed.
The mode change also showed dependence on the precursor temperature. When the precursor was
heated up to 100 °C, a helical mode, in which the discharge bent to form a curve and spun in the tube
around the central axis, occurred instead of the centered concentrated mode. The deposition profile
obtained by the profilometer showed that in general the as-deposited copper film is thicker at the
center and thinner toward edges. At a power of 3.0 W, a deposition rate of 8.3 nm/min and an
electrical resistivity of ≤ 1×10-7 ohm-m, which is close to that of bulk iron, can be obtained. Similar to
those copper films deposited by traditional CVD methods, the films obtained using the
He/H2/Cu(acac)2 plasma jet consisted of nano-grains (~ 50 nm in size), indicating the island growth
mechanism. The XPS results showed that the surface of the conductive portion (reddish brown region)
of the as-deposited film was mainly composed of metallic copper (60–80 at.% in total), rather than
copper oxide, whereas carbon and oxygen (20–40 at.% in total) were still observed. The
concentrations of the carbon and oxygen impurities, mainly attributed to the precursor ligands, can be
significantly reduced by applying a higher discharge power. It was also shown that a higher power led
to a lower concentration of the carbonyl groups in the film. In addition, the copper films exhibit better
stability (more resistant to corrosion), compared to the copper films deposited using thermal
evaporation. This He/H2/Cu(acac)2 DBD jet enables the copper films to be deposited on various
substrates (e.g., glass, silicon, plastic, and cardboard) at low temperature.
Accomplishment:
 A patent (the same one mentioned in the previous project) based on this work was
granted/issued
 A journal paper was drafted to be submitted

5
Project 4 – Plasma Physics Project @ Texas A&M (2009-2012):
Characteristics of Precursor-Dependent Multiple Breakdowns in Helium
Dielectric Barrier Discharge Jet
Project Feature: A fundamental study on plasma physics which discovered several unknown
discharge breakdown processes (e.g. multiple breakdown) in plasma jets
Required Skills: Plasma-impurity interaction, plasma physics, electrical characterization, high-speed
ICCD imaging, photomultiplier (PMT)
Abstract: Multiple-breakdown phenomenon in a helium (He) plasma jet was characterized. It was
observed that after MMA precursors were added to the plasma jet, the discharge current pulse at each
half cycle changed from a single broad pulse to multiple broad pulses when a sufficient voltage was
introduced. The number of the broad pulses in the He/MMA plasma jet increases with rising power.
There was always only one broad pulse per half cycle regardless of the applied power in the case using
pure He plasma jet. We observed that the higher the applied power the longer the pulse duration. The
experimental results from the discharge current traces, PMT traces, and ICCD images indicated that
each broad current pulse observed at the positive half cycle consists of several short-duration (1–2 s)
small current pulses which overlap. In other words, the “broadened current pulse” in the He and
He/MMA plasma jets can be deconvolved into several small pulses. Each short-duration pulse (one
breakdown) was found to result from an ionization wave front and a trailing plasma channel when the
wave travels from the anode to cathode. In both He and He/MMA cases, the number of the
short-duration pulses increases as the discharge power rises. The generation of more short-duration
current pulses (more breakdowns) causes the formation of a single broadened pulse (4–16 s) in the
He plasma jet with longer duration but several (2–3) broadened pulses (2–4 s) in the He/MMA
plasma jet. The separation of the broadened pulses in the He/MMA case is due to the higher
breakdown voltage and the faster decay of electron density in each single short-duration pulse,
compared to the case using pure helium. The fast current disappearance can be likely attributed to the
electron energy loss and attachment to the MMA and formed radicals.
Accomplishment:
 A journal paper (IEEE Transactions on Plasma Science, vol. 40, pp. 2931 (2012)) based on
this work was published

6
(2009-2012):
Bacterial Growth Inhibition Using Polymer Films Deposited by Plasma Jet
Project Feature: A pioneer work which first demonstrated the feasibility of direct deposition of
coatings on biological surfaces in open air conditions for bacterial growth inhibition
Required Skills: Plasma medicine, interaction of plasma with microbes, microbiology
Abstract: The interaction of the plasma and the deposited coating with bacteria (E. coli) on agar was
experimentally investigated. MMA addition to the He DBD plasma jet enhanced the bactericidal
efficacy of the plasma jet (i.e., faster bacterial inactivation using He/MMA DBD jet was observed,
compared to that by pure He plasma). The experimental results showed that the deposited PMMA by
the plasma jet served as a barrier, which significantly inhibited the growth of the bacteria from the 2nd
inoculation in which the bacterium suspensions were directly added on top of the deposited film. The
results with various plasma treatment times showed that the bacterial growth inhibition efficacy was
influenced by the film thickness and the type of bacterial strains. With this new plasma-jet application,
we demonstrated that wounds can be not only sterilized but also protected by the deposited coatings
(like bandage) from bacterial invasion and growth. In addition, the attempt of AP-PECVD on pigskin
using both the He/MMA DBD jet and the He/H2/Cu(acac)2 DBD jet was made for preliminary study
of the plasma-tissue interaction and the features of the coatings grown on tissue. PMMA films were
successfully deposited on the pigskin and they exhibited a greater diameter than that of the glass tube,
similar to the results on the microscope slides and agar. The deposition of reddish brown copper films
with a size (~4 mm) close to the inner dimension of the glass tube on pigskin was also achieved. A
proper discharge power was required to prevent tissue damage and charring due to the excess heat
from plasma.
Accomplishment:
 A journal paper (Applied Physics Letters, vol. 101, pp. 074107 (2012)) based on this work was
published

7
Project 6 – Plasma Technology, Process and Prototype Development Project @
Texas A&M (2009-2012):
Design and Development of Various Plasma Systems for Different Applications
Required Skills: Prototype design, plasma engineering, electrical engineering, mechanical
engineering, very strong hands-on skill

8
Project 7 – Equipment Engineering Project @ Academia Sinica (2008):
Reconstruction and Performance Improvement of a Ultra-High Vacuum
Molecular Beam Epitaxy System
Required Skills: Vacuum Technology, electrical engineering, mechanical engineering, 3rd
party
coordination capability, very strong hands-on skill
Project Summary:
 Dissembled, cleaned, reconstructed, and upgraded a MBE system which had severe oil
contamination
 Tested vacuum leakage on all the flanges and baked out the chamber to release the adsorbed
particles.
Accomplishment:
 The upgraded MBE can reach down to 10-10
Torr and can be used to grow materials with low
evaporation temperature

9
Project 8 – Nanomaterial Fabrication & Characterization Project @ Academia
Sinica (2008-2009):
Fabrication of Semiconductor Nanostructures and Characterization of Their
Room-Temperature Ferromagnetism
Project Feature: Non-magnetic semiconductor materials may exhibit magnetic properties when their
dimensions are in several nanometers
Required Skills: PVD, material science, molecular beam epitaxy (MBE), ultra-high vacuum
technology, nano-technology, XRD, SEM, AFM, vibrating sample magnetometer (VSM), SQUID
magnetometer
Abstract: In this study, room-temperature ferromagnetism was measured in amorphous germanium
(Ge) nanoparticles by the vibrating sample magnetometer (VSM) and SQUID magnetometer. Ge
nanoparticles with various sizes and distribution were fabricated by depositing Ge layers on top of
silica nanospheres. The sizes and the distributions of Ge nanoparticles were manipulated by the sizes
of the silica nanospheres and the thickness of the Ge layers. Different Ge nanoparticles were also
collected by adjusting the helium gas pressures in inert gas condensation. The magnetization of
samples was influenced by both the size and the density of Ge nanoparticles. Larger saturation
magnetizations were observed in the sample with smaller size of Ge nanoparticles. As the density
was increased, the magnetic coupling among Ge nanoparticles was enhanced due to reduced
interparticle distances. The appearance of room-temperature ferromagnetism was attributed to the
magnetic coupling among Ge nanoparticles, in which magnetic moments may arise from both defects
in amorphous structures and the surface effect of nanoparticles. By capping a metal layer over the Ge
nanoparticles, the magnetizations were also increased through the enhancement of the magnetic
coupling. Further investigation of the room-temperature ferromagnetism in the nanostructures of
different semiconductor materials, such as Si, Sb and Bi, was also conducted. Preliminary results
showed that Si and Sb nanostructured fabricated on nanospheres also exhibited room-temperature
ferromagnetism.
Accomplishment:
 A journal paper (Taiwan Nano Newsletter, vol. 18, pp. 40 (2009)) related to this work was
published

10
Project 9 – CMOS-MEMS Design & Capacitive Sensing Project @ National Tsing
Hua University (2006):
Design of a 2-D Verical Comb-Drive Micromirror with Differential Capacitance
Sensing Circuit
Project Feature: A new 2-D micromirror design which integrated the differential capacitance sensors
using CMOS-MEMS technology
Required Skills: CMOS, MEMS, semiconductor process, Cadence Tool, CoventorWare, HSPICE
Abstract: A new two-dimensional vertical comb-drive micromirror with integrated differential
capacitance sensing circuit, which is based on the TSMC 0.35 µm 2P4M Mixed Signal CMOS-MEMS
process, was designed and analyzed. In this design, the metal layers including Metal-1, Via12, and
Metal-2 were employed to form the lower comb electrodes; while Metal-3, Via34, and Metal-4 were
utilized for the upper comb electrode. Not all the comb electrodes were used for micromirror actuation.
Instead, some lower comb electrodes served as the capacitance sensing elements. Additional upper
comb electrodes were designed to achieve the differential capacitance sensing capability. When a
positive potential was applied to the outer actuators and the gimbal was grounded, the gimbal started
to rotate, leading to an increase in the capacitance of lower sensing comb electrodes and a decrease in
the capacitance of upper sensing comb electrodes. Furthermore, the differential capacitance can be
obtained. A Correlated Double Sampling (CDS) differential capacitance sensing circuit was also
designed to convert the differential capacitance to a voltage output. The voltage output can be used not
only to calculate the rotation angle but also to achieve feedback control. The CDS sensing circuit can
effectively reduce the flicker noise, offset voltage, switch charge injection, clock feedthrough and
kT/C noise. The analytical results showed that rotation angles of ±1° and ±0.72° with respect to the
mirror- and gimbal- axis can be obtained. A change in the rotation angle led to a change in the
capacitance (120-130 fF) of the sensing electrodes, which led to a voltage change ranging from -7 to 2
V at the output of the CDS differential capacitance sensing circuit based on the HSPICE simulation
results.

11
Project 10 – CMOS-MEMS Design & Fabrication Project @ National Tsing Hua
University (2004-2006):
Design and Fabrication of Two-Dimensional Vertical Comb-Drive Micromirrors
in an Optical-Tweezers System
Project Feature: Design of new 2-D micromirrors based on CMOS-MEMS fabrication process,
which facilitates the integration of the readout circuit with MEMS
Required Skills: CMOS, MEMS, semiconductor process, Cadence Tool, CoventorWare, ANSYS,
SEM, wet & dry etching, 3-D interferometer
Abstract: A novel CMOS two-dimensional (2-D) gimbaled angular vertical comb-drive (AVC)
micromirror with curled-hinged structures and an octagonal-shaped mirror was designed for the
application in an optical-tweezers system. The 2-D mirror is fabricated by TSMC 0.35 µm 2P4M Mixed
Signal CMOS-MEMS process followed by a subsequent wet etching technique. The CMOS 2-D
micromirror has the advantages of low cost, high fill factor, and capability of integration with readout
circuit. The analytical and modeling results showed that the proposed mirror has larger rotation angles,
compared to the conventional rectangular staggered vertical comb-drive (SVC) micromirrors. Rotation
angles of ±2.1° and ±1.8° with respect to the mirror- and gimbal- axis can be achieved in this AVC
octagonal 2-D micromirror.
Accomplishment:
 Published a conference paper on the design of the CMOS-MEMS micromirror

12
Software

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Project 1 – User Interface Design & Data Processing Project:
Tool Path Modification for 3D Printing
Project Feature: A Windows desktop application software to automatically modify G code file
Required Skills: C++ programming, MFC, data structure, data processing, file I/O, machine code
Abstract: This application was developed to modify tool paths for 3D printing processes. The whole
concept can be illustrated by the figure below. The original tool paths are just very simple 90 degree
paths: 12 in x+ direction, 23 in y+ direction, 34 in x- direction, 45 in y+ direction, and so on
so forth. The label E along the lines means that when the printer extrusion head moves from one point
to another, it will extrude filaments. The new paths after modification are a little bit different. Instead
of starting from point 1, the printing head starts from a point (point 1-pre) which has some distance
away from point 1. And when the printing head moves from 1-pre to 1, no filament is extruded. And
then from 1 to 2, similar to the original paths, the extrusion will be turned on. After extrusion when the
tool head arrives point 2, the extrusion will stop but keep moving to point 2-post. This application
allows the user 1) to import a file with .gcode format, 2) to tune the overshoot distance and moving
speeds during the overshoots, and 3) to export a new file with modified G code.
*Please visit https://clifftsai.wordpress.com/ for more detailed information

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Project 2 – User Interface Design Project:
Sales Log Interface
Project Feature: A Windows desktop application software to allow the user to record, manage, and
track sales information
Required Skills: C++ programming, MFC, GUI design, data processing, file I/O, sorting using text
callbacks
Abstract: This application was developed to allow the user to manage the sales information more
efficiently. It has edit boxes to receive the information about the sales items and a main list control to
display the items with their detailed information the user types in. The main list control also has a sort
function which will be enabled when the user clicks the column header. There is a second list control
to show the dimension, weight, and price for the box used for international shipping. Both list controls
allow the user to add, update, and remove items. The application will calculate the total expense, the
total income, and the net profit automatically. The item information on the list can be further saved to a
file, which can be loaded back whenever the user wants to. In addition, this application has printing
function, which allows the user to print a summary report.
*Please visit https://clifftsai.wordpress.com/ for more detailed information

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Project 3 – Control System Development & User Interface Design Project:
Control of Two-Dimensional Vertical Comb-Drive Micromirrors in an
Optical-Tweezers System
Project Feature: Design of a nonlinear control for 2-D veritical comb-drive micromirrors and an
image processing interface for cell recognition in the optical-tweezers system using
MATLAB/Simulink
Required Skills: MATLAB, Simulink, controller design, mathematical modeling of physical systems,
image processing
Abstract: A nonlinear controller for MEMS vertical comb-drive micromirrors, which were used in an
optical-tweezers system to control the optical tweezers, was designed. The controller combines
adaptive control and sliding control to deal with parametric uncertainties and nonlinear torque inherent
in the vertical comb-drive micromirrors, respectively. With the nonlinear controller, the vertical
comb-drive micromirrors can be operated linearly and robustly. The simulation results show that the
micromirror integrated with the proposed controller can follow a desired trajectory of 10-Hz sinusoid
with tracking error of less than 0.001° in 0.01 seconds. In addition, an image processing user interface
was designed and developed for cell recognition in the optical-tweezers system. The user interface was
used to generate the desired trajectory to the nonlinear control. It also had capabilities for automatic
cell recognition, path planning for a single laser spot, object position display, and manual operation.
Accomplishment:
 Published a conference paper on the control of the CMOS-MEMS micromirror

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Project 4 – User Interface Design & Process Simulation Project:
Design and Development of a Computer-Aided Manufacturing (CAM) Graphic
User Interface (GUI) for an Excimer Laser Based Submicron Fabrication System
Project Feature: Developed a CAM GUI software which can display the simulated fabrication
animation and result for an excimer laser submicro-machining system
Required Skills: C++/MFC programming, interpolation, fabrication path planning, data processing,
OpenGL, slicing
Abstract: A computer-aided manufacturing (CAM) software with a graphic user interface (GUI) was
designed and developed using C++ with MFC library. The CAM software was used to generate
machining codes for an excimer laser based submicron fabrication system, whose application was to
manufacture metallic free-form micro-molds. The GUI allowed users to import STL model and input
the fabrication parameters, such as laser spot size, laser wavelength, stage travel speed, and material
removal rate. Furthermore, this software has the capability to display the animation of the simulated
fabrication process and show the final appearance of the laser-fabricated micro-mold.
Accomplishment:
 3rd place in the National Contest of Student Project

Cliff Tsai Portfolio_04272016 - HWSW

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