Holst Centre and imec have developed a prototype flexible health patch weighing just 10g – half the weight of current products. The patch uses real-time electrocardiogram (ECG), tissue-contact impedance and accelerometer information to accurately monitor physical activity. Advanced system in package (SiP) technology from SHINKO ELECTRIC INDUSTRIES CO., LTD. resulted in an electronics module measuring less than two by two centimeters. The recorded data are wirelessly sent to an mobile device via Bluetooth Smart. Dedicated software algorithms deduce physical activity-specific energy expenditure. The high accuracy algorithms, low power consumption, and small size and weight make it ideal for consumer applications.

A growing public interest in healthy living is driving the emergence of activity monitors, with a number of devices already available that count the steps you take or the calories you burn. Heart rate is a key input in determining activity levels; hence monitors that can be worn comfortably on the chest offer the greatest accuracy. This increases the demand for small, lightweight personal health monitors that can flex and move with your body, improving the quality of the monitoring of physiological parameters of a patient.

The novel flexible health patch makes such applications possible. Combining ultra-low power electronics and flexible electrode technology, it includes a 1-lead ECG, a tissue-contact impedance sensor and a 3D accelerometer for physical activity monitoring. Data is processed and analyzed locally, and relevant information is transmitted via Bluetooth Smart link.

At the heart of the flexible health patch is an ECG System-On-Chip (SoC), a mixed signal ASIC. It is custom designed to provide ECG monitoring and high processing power at an extremely low energy consumption. The ECG SoC has been designed to run algorithms for motion artifact reduction and beat-to-beat heart rate computation. It has additional computation power to run application-specific algorithms such as epileptic seizure detection, energy expenditure estimation or arrhythmia monitoring.

The flexible health patch acquires, processes and communicates data on a minimal energy budget, allowing extended use with smaller batteries. When computing and transmitting the heart rate, the entire system current consumption is 280µA at 2.1V, running continuously for few days on a 15mAh Lithium Polymer battery. The Bluetooth Smart link adds a standardized plug-and-play communication gateway to mobile devices such as smartphones and tablets.

Innovative SiP technology for packaging electronic devices based on a high-density organic substrate enabled the integration of all functionality into a small module measuring just 17.4 mm x 17.4 mm. This represents a PCB area reduction of 52% compared to previous generations of the module. The novel technology for packaging electronic devices from SHINKO ELECTRIC INDUSTRIES CO., LTD. uses a high-density organic substrate to reduce overall system size.

The module was integrated into a flexible and stretchable patch. The design combines system in foil technology with stretchable, integrated electrodes to create a lightweight patch that adapts dynamically to curving and bending surfaces and can be worn comfortably on the chest for extended periods. The module’s small size and the flexibility of the patch reduce motion artifacts and thus provide more accurate and reliable monitoring and brings the technology closer to consumers’ needs.