What are the types of wearable sensors?

 In recent years, the sales of smart wearable devices have continued to rise, and the categories have become more abundant, covering functions such as health monitoring, social entertainment, and virtual reality.

　　Wearable electronic devices refer to computing devices, textiles and clothing with integrated electronic technology or other intelligent functions, such as watches, hats, shirts and glasses. These wearable electronic products enhance user creativity, intelligence, communication skills, memory and physical senses.

　　 Wearable technology relies on sensors to measure how human movements provide consumers with data about themselves. With the development of sensor technology, wearable devices now have deeper measurement capabilities. In this regard, today I counted the types of wearable sensors.

  Accelerometer

　　Accelerometer is a sensor used in wearable devices, which can detect gravity and linear velocity. At the same time, the accelerometer can also program measurement data for different purposes. For example, a running user can access his or her maximum speed output and acceleration. In addition, the accelerometer can track sleep patterns.

  Gyro

　　 Gyroscope is also a common wearable sensor. They differ from accelerometers in that they only record angular acceleration. In some embodiments, an accelerometer is used to measure rotational acceleration, and some systems want to combine the two to eliminate filtering errors. The gyroscope improves the accuracy of tracking data and provides multiple types, including gas bearings, mechanical bearings and optical bearings.

　　 Magnetometer

　　 Magnetometer can be integrated with accelerometer and gyroscope to form an inertial measurement unit (IMU). All these sensors can have three axes, very similar to a compass, and can improve balance. Gyroscopes and accelerometers are usually used with them, while magnetometers match them by filtering the direction of motion.

　　Global Positioning System (GPS)

　　 GPS is a commonly used sensor on many devices such as smart phones and smart watches. It is used to scan and notify the user of its location. Information is sent to satellites to quantify the exact location and time. This acts as a transmitter and receiver, where information is returned to the sensor to inform the location.

　　 Heart rate sensor

　　 As the name suggests, a heart rate sensor is used to measure heart rate.

There are many technologies and sensors that can be used to measure heart rate. The use of capacitive sensing to idealize electrodes (sensors) and skin for measurement is one of the methods; photoplethysmography is also a method, which is a method that uses light to Technology to track changes in blood flow. Fitness trackers such as Fitbit use photodiodes to measure heart rate: continuous green light is transmitted to the wearer's skin to measure the light absorption of the photodiode and to calculate pulses. The increase in blood passing through the user's blood, the more light the diode absorbs.

　　 Pedometer

　　Pedometers are usually located in wearable devices that pay attention to physical health, and can count the user's steps while running or walking. There are two variants of the pedometer: electronic and mechanical.

　　 The former is the most popular form today, and relies on MEMS technology to improve efficiency, but it still operates based on the principle of a mechanical pedometer.

　　The latter uses the pendulum to evaluate the pace of the user of the pedometer. The pedometer at both ends uses a tiny metal pendulum, one of which has screws. Whenever the user takes a step, the hammer will swing and hit another, then return to its original position. The mechanism is connected to the electronic counting circuit by a spring. First of all, there is no current, so whenever the hammer hits the other side, it breaks open. Therefore, current starts to flow. Once the pendulum moves back to its original point, the circuit will close again and the pendulum rotation will restart.

  Pressure Sensor

　　 Normally, pressure sensors work through strain gauges. When pressure is applied to the sensor, the electrical circuit will cause a change in resistance. Mechanical quantities such as force can be observed in many ways and converted into resistance-related electronic measurements.

　　 This method of measuring pressure is achieved by building a Wheatstone bridge, which can track static or dynamic resistance changes. The sensing device will be configured with one, two or four arms in the Wheatstone bridge, the number depends on the use of the device (the number of tension and compression), and then the sensor mechanism allows them to be integrated into external factors, such as ball contact monitoring equipment.

　　 Microcontroller that integrates sensors into wearable devices

　　 Microcontroller is a key component of wearable devices. It is usually regarded as a small computer (system on a chip), which allows the integration of the Internet of Things (IoT) with the required applications. Most importantly, it eliminates the trouble of using many electronic components to perform different functions on a single chip. It is most suitable for use in wearable technology due to its ease of programming, reprogramming, cost, size, connection with other sensors, and the ability to handle complex functions (including graphic displays). Versatility allows the microcontroller to be customized to meet customer needs.

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