Physical sensors commonly used in smart home systems

Many sensors are used in the smart home system, which is necessary. Today we introduce common physical sensors.

The physical sensor is a sensor that detects a physical quantity. It is a device that uses some physical effects to convert the measured physical quantity into a signal in the form of energy that is easy to process. The output signal and the input signal have a definite relationship. The main physical sensors are photoelectric sensors, piezoelectric sensors, piezoresistive sensors, electromagnetic sensors, pyroelectric sensors, optical fiber sensors, etc.

As an example, let us look at the more commonly used photoelectric sensors. This 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 optical signals. The main principle is the photoelectric effect: when light strikes a substance, the electrical effect on the substance changes. The electrical effect here includes electron emission, conductivity, and potential current. Obviously, devices that can easily produce such effects become the main components of photoelectric sensors, such as photoresistors.

In this way, we know that the main work flow of the photoelectric sensor is to receive the corresponding light irradiation. The light energy is converted into electrical energy through a device like a photoresistor, and then the required output is obtained through amplification and noise removal processing. electric signal. There is a certain relationship between the output electrical signal and the original optical signal, which is usually close to linear, so that the calculation of the original optical signal is not very complicated. The principles of other physical sensors can be compared to photoelectric sensors.

The application range of physical sensors is very wide. We only look at the application of physical sensors from the perspective of biomedicine. It is not difficult to speculate that physical sensors also 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 indirect measurement, and the relationship between blood flow and pressure detected on the body surface is used to measure the blood pressure value in the blood vessel. The sensors needed to measure blood pressure usually include an elastic diaphragm, which transforms the pressure signal into the deformation of the diaphragm, and then converts it into a corresponding electrical signal according to 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 obtain the diastolic pressure and the integrator to obtain the average pressure.

Let's look at breath measurement technology again. Breath measurement is an important basis for clinical diagnosis of lung function and is essential in surgical operations and patient monitoring. For example, when using a thermistor sensor for measuring breathing frequency, the resistance of the sensor is installed on the outside of the front end of a clip, and the clip is clamped on the nasal wing. When the flow of breathing gas passes through the surface of the thermistor, it can pass the heat. The varistor measures the frequency of breathing and the state of the hot gas.

Another example is the most common body surface temperature measurement process, although it seems easy, but it has a complicated measurement mechanism. Body surface temperature is determined by various factors such as local blood flow, heat conduction of the underlying tissue, and heat dissipation of the epidermis. Therefore, the measurement of skin temperature should take into account various effects. Thermocouple sensors are widely used in temperature measurement, usually with rod-shaped thermocouple sensors and thin-film thermocouple sensors. Because the size of the thermocouple is very small, the accuracy can be achieved in the micron level, so the temperature at a certain point can be measured more accurately, and the later analysis statistics can get a more comprehensive analysis result. This is unmatched by traditional mercury thermometers, and it also demonstrates the broad prospects of applying new technologies to scientific development.

From the above introduction, it can be seen that physical sensors have various applications only in biomedicine. The development direction of the sensor is a multifunctional, image, and intelligent sensor. As an important means of data acquisition, sensor measurement is an indispensable device for industrial production and even family life, and physical sensors are the most common sensor family. Flexible use of physical sensors is bound to create more products and better benefits , The use of good sensors in the smart home control system can greatly improve its control accuracy.

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