Expanding applications in all directions, including wearables, healthcare, and drones

As the scope of application of smart sensors expands, the types of products for each application are also diversifying.

Representative examples include the increasing adoption of sensors in smartphones, wearables, healthcare, and drones, and as the IoT era approaches, sensors with various communication functions are also attracting attention.

Sensing technology in the IoT era uses multi-sensor technology that is one level higher than existing independent and individual sensors, including physical sensors that can obtain information from tangible objects and the surrounding environment, such as traditional temperature, humidity, heat, gas, illuminance, and ultrasonic sensors, as well as remote sensing, SAR, radar, location, motion, and image sensors. Because of this, it is possible to extract more intelligent and high-dimensional information.

Accordingly, smart sensors are a general term for intelligent sensors that dramatically improve external environment detection and have signal processing such as data processing, automatic correction, self-diagnosis, and decision-making organically built in.

The new era of sensors began when sensors were widely used in early smartphones. Basic sensors such as acceleration sensors and gyro sensors were adopted in smartphones, and expanded to include pressure sensors, temperature and humidity sensors, and fingerprint recognition sensors. In addition to these, gesture sensors, proximity sensors, geomagnetic sensors, hall sensors, and RGB sensors are currently being applied to smartphones.

However, smartphone sensors have limitations in collecting data optimized for the user. In the case of the heart rate sensors in the latest smartphones, they are less effective than dedicated devices that need to continuously monitor heart rate changes through temporary measurements. This is also why wearable devices that complement this have emerged rapidly.

The sensors applied to wearable devices have the advantage of always being in contact with the consumer's body parts, enabling continuous sensing. Wearable devices provide an environment where users can enjoy content as they wish without separate input through functions such as motion recognition and voice recognition using various sensors.
Accordingly, the wearable device market is expected to record annual shipments of 485 million units by 2018. Smartwatches are expected to form a market of approximately 90 million units by 2018, taking the position of a universal product necessary for daily life.

Currently, wearable devices are being developed in various forms for each body part. When the types of wearable devices are separated by body part, wrist bands and glasses are the most developed, and by industry, products for lifestyle purposes account for the majority.

Wearable devices that use a lot of temperature, humidity, pressure, and motion sensors

Most sensors used in wearable devices are those that sense physical activity. Temperature/Humidity Sensors are combined and are mainly used in watches and sports equipment. Pressure Sensors are sensors that are often used for indoor positioning, and measure air pressure to check the current altitude and which floor you are on. This is because GPS is usually not available indoors, so you can detect slight changes in pressure to determine the altitude. For example, FitBit recognizes when you climb stairs and calculates calories for stairs and flat ground separately.

The Accelerometer Sensor measures the acceleration or impact of a moving object. It is a sensor used in all activity trackers and measures the efficiency of movement. The Gyro Sensor measures how the angle of the current sensor is twisted and can recognize the three axes X, Y, and Z separately.

Motion Tracking Sensors that measure movement can detect whether the user is walking or running, and can also recognize whether the user is riding a bicycle or a car. Heart Rate Sensors that measure heart rate measure the human heart rate (ECG), convert BPM (beats per minute) into a number and transmit it to other devices. Usually, it works by shining light on the skin and reading the movement pattern of blood flowing under the skin.

For example, sensor-type products that measure heartbeat and electrocardiogram on the chest near the heart area have been developed, and there are glove-type products that can be used for gaming, lifestyle, and entertainment purposes based on Bluetooth. Products that apply call functions using microphones and receiving sensors have been developed, and socks and insole-type products that use pressure sensors have also been released.

Sweat Sensor is an auxiliary sensor that accurately measures the amount of exercise. Sweat acts through the sympathetic nervous system, and measures the amount of exercise more accurately. A UV sensor (Ultra-violet Sensor) is a sensor that measures ultraviolet rays and uses the photoelectric reaction effect with a film that is sensitive to ultraviolet rays.

Even blood sugar sensors used in healthcare devices

The aforementioned sensors are mostly used in healthcare devices, and in particular, oxygen saturation sensors and blood sugar sensors are applied for diagnosis and prevention.

The Pulse Oximeter Sensor measures the oxygen saturation in the blood (infrared, ultraviolet), and measures the state of hemoglobin in the blood using a light signal from a composite light source. The Blood Sugar Sensor measures blood sugar in the bloodstream of the human body, and measures blood sugar levels by irradiating the skin with infrared light and using the absorbance of the light.

Acceleration and gyro sensors essential for drones

Accelerometer and gyro sensors are essential sensors for unmanned aerial vehicles and drones.

If you use Arduino as the main controller, you will need an acceleration and gyro sensor to perform PID control. The gyro and acceleration values are transmitted through I2C communication with Arduino.

The acceleration sensor in the drone keeps the drone level. However, since the drone is constantly moving, the acceleration sensor alone cannot accurately determine the drone's tilt, so a gyro sensor is used together. The gyro sensor can determine how much the drone is tilted and in which direction it is tilted, and the amount of rotation of the motor. However, the acceleration sensor compensates for the disadvantage of not being able to align the level unless an initial reference value is established, as errors accumulate due to sensor noise.

Park Hyo-deok, head of the Smart Sensor Business Unit at the Electronics and Telecommunications Research Institute (KETI), said, “Sensors are becoming smaller, more complex, and more intelligent as IT becomes more intelligent and convenient in our daily lives,” adding, “They will develop into a key element technology for implementing a smart society as a mediator between humans and devices and for industrial convergence.”