High resolution flexible strain sensors for biological signal measurements

This paper presents stretchable strain sensors based on Polydimethylsiloxane (PDMS)/graphite sensing resistors for potentially a variety of wearable device applications including human biological signal measurements, such as fingertip pressure monitoring for haptic feedback and high resolution arterial pulse for health diagnostics. The strain sensor uses a serpentine electrode design that can be easily fabricated in a two-step process by direct-write laser printing and pattern transfer without any lithography process. The results demonstrate several key sensing capabilities: (1) angular motion detection with a resolution of 15-degree; (2) fingertip pressure detection up to a range of 12 kPa; (3) monitoring of human pulse waves with the clear identification of the three local peaks. As such, the proposed strain sensors can be potentially used as a biological signal input device for potential applications such in virtual reality (VR) systems.