Overview
Wearable medical and healthcare devices are noninvasive systems that can autonomously monitor or support specific medical functions. The term "wearable" implies the device is worn directly on the body or integrated into clothing and designed to be used as a wearable accessory. Broadly speaking, this requires very small size and weight, autonomous operation, an onboard power supply, ease of use, and comfortable wearability.
Smart Wearable Medical Devices and Typical Architectures
Smart wearable medical devices come in many forms, such as wristbands, watches, glasses, and other wearable formats. Common functions include pedometer, heart rate monitoring, motion tracking, biopotential measurement, bioimpedance measurement, and blood oxygen measurement.
Wearable medical devices extend technologies used in traditional medical equipment. Conventional hospital equipment is usually large, complex, and power hungry, designed for high-precision clinical applications. Advances in sensors and semiconductor technology have reduced device size and power consumption, enabling wearable implementations. Many methods developed for clinical settings have migrated toward home use or been adapted into wearable products.
Wearable devices are typically noninvasive vital-sign monitors that are easy to wear and operate. To improve user experience, lower weight and lower power consumption are preferred. They also need connectivity with other consumer electronics.
Design Considerations and Key Challenges
Size Is Critical
Most wearable devices are lightweight and becoming smaller. Key considerations include:
- Smaller packages and component footprints
- Use of advanced packaging technologies to increase integration
- Minimizing external components
Ultra-Low Power
Power consumption is crucial for user experience and should be as low as possible. Because system size limits battery capacity, low quiescent current chips help achieve low overall power and extend standby time. Wearables generally require low-power microcontrollers and low-power connectivity technologies.
Ergonomics
- Design for ease of use
- Preventing accidental operation
- Sensor designs that provide high sensitivity and reliability
High Reliability
- Ability to operate across a range of environments
- Robust mechanical design to prevent damage
- Occasional requirements for water resistance
Sensor Technology
- Multi-sensor fusion
- Selection of sensor materials with good biocompatibility
- High sensitivity at low power consumption
Connectivity
- Low-power Bluetooth and Wi-Fi to connect with other smart devices
- Data synchronization and automatic application updates
