A New Water Repellent Material for Improved Wearable Motion Sensors

Physiological monitoring of human movement for applications such as gait analysis, and monitoring of patients during rehabilitation processes could soon become better with the development of a new water repellent material for making wearable motion sensors.

Wearable motion sensors are made of materials that convert the mechanical strain that arises from human movement into electrical signals. The material must be flexible, robust, and highly sensitive to both large and subtle movements.

In the new study, the researchers from the Indian Institute of Technology (IIT)-Guwahati have developed a material that promises to be superior to existing strain sensors for both sensitivity and durability.

Physiological monitoring of human movement for applications such as gait analysis, and monitoring of patients during rehabilitation processes could soon become better with the development of a new water repellent material for making wearable motion sensors.

Until now, wearable strain sensors were made of polymers or fabrics in which nanoparticles of specialized materials were embedded. The constant stretching that is used to detect motion, however, leads to wilting and eventual failure of the material.

In the new work, the researchers evolved a metal-free, chemically reactive, and conductive ink, which they deposited on a chemically reactive paper in a specific pattern. The patterned interface was found to be stable over time, through many cycles of operation. In addition, it was tolerant to abrasion, highly water repellent, and sensitive to low strain levels.

The study team was led by Dr Uttam Manna of the Department of Chemistry, and Prof. Roy Paily of the Department of Electronics and Electrical Engineering and included Ms Supriya Das, Mr Rajan Singh, Mr Avijit Das, and Ms Sudipta Bag. The scientists have published a report on their work in the journal `Materials Horizons’.

Elaborating on the usefulness of the new material could be better, Dr Manna said, “The sensor made using the material was so sensitive that it could differentiate smiling from laughing and could even detect swallowing motion. The unconventional interface holds promise for the development of devices in diverse areas including healthcare, human-machine interactions, and energy harvesting”.