Mechanical/dynamical sensors in wearable devices play a crucial role in enabling various functionalities by detecting physical changes such as the user’s movement, position, force, and pressure. These sensors, small and lightweight enough to be integrated into wearable devices, are utilized in various fields, including daily life, health management, sports activities, and industrial settings. Let’s explore the main use cases in detail:

1. Accelerometer:

An accelerometer measures the acceleration of an object and is one of the most commonly used mechanical/dynamical sensors in wearable devices. It is mainly used for the following purposes:

• Activity Tracking: Detects the user’s movements to calculate steps taken, distance traveled, and calories burned. It is also used to automatically recognize various activities such as walking, running, and climbing stairs.
• Orientation Detection: Detects the device’s tilt or rotation direction and is used for screen rotation, game control, and navigation.
• Posture Analysis: Analyzes the user’s posture to correct poor posture or analyzes exercise posture to aid in efficient exercise.
• Impact Detection: Detects sudden impacts such as falls or collisions and is used to send rescue requests in emergencies or record data at the time of an accident.

2. Gyroscope:

A gyroscope measures the rotational angular velocity of an object and is often used in conjunction with an accelerometer. It is mainly used for the following purposes:

• Precise Motion Tracking: Accurately measures rotational movements, which are difficult to measure accurately with only an accelerometer, enabling more precise motion tracking.
• 3D Space Orientation Detection: Provides information about the device’s orientation and rotation in 3D space and is used for VR/AR (Virtual Reality/Augmented Reality) content, game control, and navigation.
• Image Stabilization: Compensates for hand tremors during camera or video shooting to obtain stable images.

3. Pressure Sensor:

A pressure sensor measures the pressure applied to an object and is mainly used for the following purposes in wearable devices:

• Touchscreen: Used for touch detection and pressure sensing on touchscreens, implementing various gesture recognition and operation functions.
• Biosignal Measurement: Can be used to measure biosignals such as blood pressure and pulse by measuring the pressure applied to the wrist.
• Plantar Pressure Measurement: By attaching pressure sensors inside shoes, it is used for gait pattern analysis, posture correction, and custom insole production.

4. Strain Gauge:

A strain gauge measures the strain (deformation) applied to an object and is mainly used for the following purposes in wearable devices:

• Muscle Strength Measurement: Measures skin deformation due to muscle movement to measure the effectiveness of muscle strength training or aid in rehabilitation training.
• Joint Movement Measurement: Measures the angle of joint movement and is used for rehabilitation training and exercise analysis.

5. Inertial Measurement Unit (IMU):

An IMU is a sensor that integrates an accelerometer and a gyroscope, simultaneously measuring 3-axis acceleration and 3-axis angular velocity to provide more accurate movement and orientation information. Widely used in drones, robots, and VR/AR devices, it is used in wearable devices for high-precision motion tracking, posture analysis, and exercise analysis.

Applications in Industrial Settings:

In industrial settings, these mechanical/dynamical sensors are used to enhance worker safety and improve productivity. For example:

• Construction Sites: Used for worker fall detection, collision prevention with heavy equipment, and warning of approaching hazardous areas.
• Manufacturing Plants: Used for improving work environments through worker posture analysis and preventing musculoskeletal disorders caused by repetitive tasks.
• Logistics/Transportation: Used to prevent traffic accidents by detecting driver drowsiness and detecting sudden stops/accelerations.

As described, mechanical/dynamical sensors used in wearable devices are utilized in various ways to make our lives more convenient and safe. It is expected that even smaller, more precise, and multifunctional sensors will be developed with technological advancements.