There are many sensors to be used in smart home systems. This is a must. Today we introduce commonly used physical sensors.

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What is physical sensors in smart home systems?
Written By Calio Huang
There are many sensors to be used in smart home systems. This is a must. Today we introduce
commonly used physical sensors.
The physical sensor is a sensor that detects physical quantities. It is the use of certain physical
effects, the measured physical volume into a form of energy to facilitate the processing of the
signal device. The output signal and the input signal have a definite relationship. The main
physical sensors include photoelectric sensors, piezoelectric sensors, piezoresistive sensors,
electromagnetic sensors, pyroelectric sensors, and optical fiber sensors. As an example, let us
look at the more commonly used photoelectric sensors. This kind of sensor converts the optical
signal into an electrical signal. It directly detects the radiation information from the object and
can also convert other physical quantities into an optical signal. The main principle is the
photoelectric effect: When the light is irradiated to the material, the electrical effect on the
material changes, and the electrical effects here include electron emission, conductivity, and
potential current. Obviously, a device that can easily produce such an effect becomes a major
component of a photoelectric sensor, such as a photoresistor. In this way, we know that the main
working process of a photoelectric sensor is to receive the corresponding light, convert the light
energy into electricity through a device such as a photosensitive resistance, and then obtain the
required output by amplification and denoising electric signal. The output electrical signal here
has a certain relationship with the original optical signal, which is usually close to a linear
relationship so that the calculation of the original optical signal is not very complicated. The
principles of other physical sensors can be compared to optical sensors.

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The range of application of physical sensors is very extensive. We only look at the application of
physical sensors from the perspective of biomedical science. It is not difficult to infer that physical
sensors have important applications in other aspects.
For example, blood pressure measurement is the most common type of medical measurement.
Our usual blood pressure measurement is an indirect measure of the blood pressure in the vessel
by measuring the relationship between blood flow and the pressure detected by the body
surface. The sensors needed to measure blood pressure usually include an elastic diaphragm that
transforms the pressure signal into a deformation of the diaphragm and then converts it into a
corresponding electrical signal based on the strain or displacement of the diaphragm. At the peak
of the electrical signal, we can detect the systolic pressure. After passing through the inverter and
the peak detector, we can get the diastolic pressure. The average pressure can be obtained
through the integrator.
Let's take another look at the breath measurement technique. Respiratory measurement is an
important basis for the clinical diagnosis of lung function and is essential for surgery and patient
monitoring. For example, when using a thermistor sensor for measuring respiratory rate, mount
the sensor's resistance on the outside of the front end of a clip, clip the clip over the nose, and
pass the heat as the flow of breathing gas flows from the thermistor surface Sensitive resistance
to measure the frequency of breathing and the status of hot gas.
Another example of the most common body surface temperature measurement process,
although it seems easy, it has a complex measurement mechanism. The body surface
temperature is determined by various factors such as the local blood flow, the heat conduction of
the underlying tissue, and the heat dissipation of the epidermis. Therefore, the measurement of
the skin temperature must take into account various influences. Thermocouple sensors are more
commonly used in the measurement of temperature, usually rod-shaped thermocouple sensors
and thin-film thermocouple sensors. Because the size of the thermocouple is very small and the
accuracy is relatively high, it is possible to measure the temperature at a certain point accurately.
With the help of later analysis statistics, a more comprehensive analysis result can be obtained.
This is incomparable with the traditional mercury thermometer, but also shows the broad
prospects for the application of new technologies to the scientific development.
As can be seen from the above description, only in biomedical, physical sensors have a wide
range of applications. The development direction of the sensor is a multifunctional, imaged,
intelligent sensor. Sensor measurement as an important means of data acquisition is
indispensable for industrial production and even family life, and physical sensors are the most
common family of sensors. The flexible use of physical sensors will inevitably create more
products and better benefits, Use good sensors on smart home control system can greatly
improve its control accuracy.