Common sensors in IoT

In the era of the Internet of Everything, sensors are one of the most critical components.Sensors are used to collect data on everything from drones and cars to wearables and augmented reality headsets.Let me introduce to you 6 sensors that are widely used in the field of Internet of Things.

According to the general division, the Internet of Things is structurally divided into three parts: the perception layer, the network layer and the application layer.Among them, the perception layer plays a crucial role as the data source of network layer transmission and the data basis of application layer calculation. The important components that constitute the perception layer are various sensors.

According to different classification methods, sensors can be divided into different categories. For example, according to the measured non-electrical physical quantity, it can be divided into pressure sensors and temperature sensors.

According to the working method of converting non-electrical physical quantities into electrical physical quantities, it can be divided into energy conversion type (no additional energy access during operation) and energy control type (additional energy access during operation) and so on. In addition, according to the manufacturing process, it can be divided into ceramic sensors and integrated sensors.

We start with a variety of measured non-electrical physical quantities, and take stock of those common sensors in the field of IoT.

Light sensor

The working principle of the light sensor is to use the photoelectric effect to convert the intensity of ambient light into a power signal through a photosensitive material. According to the photosensitive materials of different materials, the light sensor will have various divisions and sensitivities.

Optical sensors are mainly used in ambient light intensity monitoring of electronic products.The data shows that in general electronic products, the power consumption of the display is as high as more than 30% of the total power consumption. Therefore, changing the brightness of the display screen with the change of the ambient light intensity has become the most critical energy saving method. In addition, it can also intelligently make the display effect softer and more comfortable.

Distance sensor

Distance sensors can be divided into two types, optical and ultrasonic, according to the different pulse signals sent out during ranging. The principle of the two is similar. Both send a pulse signal to the measured object, receive the reflection, and then calculate the distance of the measured object according to the time difference, angle difference and pulse speed.

Distance sensors are widely used in mobile phones and various smart lamps, and products can change according to different distances of users during use.

Temperature Sensor

The temperature sensor can be roughly divided into contact type and non-contact type from the perspective of use. The former is to let the temperature sensor directly contact the object to be measured to sense the temperature change of the measured object through the temperature sensitive element, and the latter is to make the temperature sensor. Keep a certain distance from the object to be measured, detect the intensity of infrared rays radiated from the object to be measured, and calculate the temperature.

The main applications of temperature sensors are in areas closely related to temperature, such as intelligent heat preservation and ambient temperature detection.

Heart rate sensor

Commonly used heart rhythm sensors mainly use the sensitivity principle of infrared rays of specific wavelengths to changes in blood.Due to the periodic beating of the heart, the regular changes in the flow rate and volume of the blood in the blood vessel under test are caused, and the current number of heartbeats is calculated through signal noise reduction and amplification processing.

It is worth mentioning that the intensity of the infrared rays emitted by the same heart rhythm sensor penetrating the skin and reflecting through the skin is also different depending on the skin tone of different people, which causes certain errors in the measurement results.

In general, the darker a person’s skin tone is, the harder it is for infrared light to reflect back from the blood vessels, and the greater the impact on measurement error.

At present, heart rate sensors are mainly used in various wearable devices and smart medical devices.

Angular velocity sensor

Angular velocity sensors, sometimes called gyroscopes, are designed based on the principle of conservation of angular momentum. The general angular velocity sensor is composed of a rotatable rotor located at the axis, and the movement direction and relative position information of the object are reflected by the rotation of the rotor and the change of angular momentum.

A single-axis angular velocity sensor can only measure changes in a single direction, so a general system needs three single-axis angular velocity sensors to measure changes in the three directions of the X, Y, and Z axes.At present, a common 3-axis angular velocity sensor can replace three single-axis sensors, and it has many advantages such as small size, light weight, simple structure, and good reliability. Therefore, various forms of 3-axis angular velocity sensors are the main development. trend.

The most common angular velocity sensor usage scenario is mobile phones. Famous mobile games such as Need for Speed mainly use the angular velocity sensor to generate an interactive mode in which the car sways from side to side. In addition to mobile phones, angular velocity sensors are also widely used in navigation, positioning, AR/VR and other fields.

Smoke sensor

According to different detection principles, smoke sensors are commonly used in chemical detection and optical detection.

The former uses the radioactive americium 241 element, and the positive and negative ions generated in the ionized state move directionally under the action of the electric field to generate stable voltage and current.Once smoke enters the sensor, it affects the normal movement of positive and negative ions, causing corresponding changes in voltage and current, and the strength of smoke can be judged by calculation.

The latter passes through the photosensitive material. Under normal circumstances, the light can completely irradiate the photosensitive material to generate stable voltage and current.Once smoke enters the sensor, it will affect the normal illumination of the light, resulting in fluctuating voltage and current, and the strength of the smoke can also be determined by calculation.

Smoke sensors are mainly used in the fields of fire alarm and security detection.

In addition to the sensors mentioned above, air pressure sensors, acceleration sensors, humidity sensors, fingerprint sensors, and fingerprint sensors are common in the Internet of Things.Although their working principles are different, the most basic principles are all mentioned above, that is to convert the to-be-measured into electrical quantities through light, sound, material and chemical principles, but most of them are based on specific fields in general principles. On the basis of specific upgrades and extensions.

Since their invention in the industrial age, sensors have played a vital role in fields such as production control and detection metrology.Just like human eyes and ears, as a carrier for receiving information from the outside world in the Internet of Things and an important front-end of the perception layer, sensors will usher in a high-speed development period with the popularization of the Internet of Things in the future.