Soft, Sensitive And Stable Sensors For Wearables

Researchers in South Korea have developed a wearable pressure sensor for health monitoring applications and early disease diagnosis.

AsianScientist (Feb. 10, 2020) – Seeking to enable real-time health monitoring and for the early diagnosis of diseases, researchers in South Korea have developed soft pressure sensors that can be embedded in various wearable technologies. Their findings are published in the journal Advanced Healthcare Materials.

Wearable soft pressure sensors have great potential for health monitoring and for the early diagnosis of diseases. Crucially, the sensors used in devices must be sensitive, inexpensive and stable for continuous health monitoring.

Conventional solid-state soft pressure sensors using functional materials including carbon nanotubes and graphene have showed great sensing performance. However, these sensors suffer from limited stretchability, signal drifting and long-term instability due to the distance between the stretchable substrate and the functional materials.

To overcome these issues, liquid-state electronics using liquid metal have been introduced for various wearable applications. Of these materials, galinstan, a eutectic metal alloy of gallium, indium and tin, has great mechanical and electrical properties that can be employed in wearable applications. But today’s liquid metal-based pressure sensors have low-pressure sensitivity, limiting their applicability for health monitoring devices.

In this study, researchers led by Professor Park Inkyu at the Korea Advanced Institute of Science and Technology developed a rigid microbump array-integrated, liquid metal-based soft pressure sensor. With the help of 3D printing, the integration of a rigid microbump array and the master mold for a liquid metal microchannel could be achieved simultaneously, reducing the complexity of the manufacturing process.

The researchers noted that the integration of the rigid microbump and the microchannel paved the way for a pressure sensor that has an extremely low detection limit and enhanced pressure sensitivity compared to previously reported liquid metal-based pressure sensors. The proposed sensor also has a negligible signal drift over 10,000 cycles of pressure, bending and stretching. It also exhibited excellent stability when subjected to various environmental conditions.

As a validation of their technology, the researchers embedded their sensor into a wearable wristband device and demonstrated that it could be used to continuously monitor one’s pulse during exercise. The device was also suitable for noninvasive cuffless BP monitoring and could be integrated with a wireless wearable heel pressure monitoring system.

“It was possible to measure health indicators including pulse and blood pressure continuously as well as pressure of body parts using our proposed soft pressure sensor,” said Park.

“We expect [our sensor] to be used in health care applications, such as for the prevention and monitoring of pressure-driven diseases, including pressure ulcers, in the near future. There will be more opportunities for future research including a whole-body pressure monitoring system related to other physical parameters,” he concluded.

The article can be found at: Kim et al. (2019) Wearable Sensors: Highly Sensitive and Wearable Liquid Metal‐Based Pressure Sensor for Health Monitoring Applications: Integration of a 3D‐Printed Microbump Array with the Microchannel.


Source: Korea Advanced Institute of Science and Technology; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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