Transparent and Flexible Vibration Sensor Based on a Wheel-Shaped Hybrid Thin Membrane

Abstract

With the advent of human–machine interaction and the Internet of Things, wearable and flexible vibration sensors have been developed to detect human voices and surrounding vibrations transmitted to humans. However, previous wearable vibration sensors have limitations in the sensing performance, such as frequency response, linearity of sensitivity, and esthetics. In this study, a transparent and flexible vibration sensor was developed by incorporating organic/inorganic hybrid materials into ultrathin membranes. The sensor exhibited a linear and high sensitivity (20 mV/g) and a flat frequency response (80–3000 Hz), which are attributed to the wheel-shaped capacitive diaphragm structure fabricated by exploiting the high processability and low stiffness of the organic material SU-8 and the high conductivity of the inorganic material ITO. The sensor also has sufficient esthetics as a wearable device because of the high transparency of SU-8 and ITO. In addition, the temperature of the post-annealing process after ITO sputtering was optimized for the high transparency and conductivity. The fabricated sensor showed significant potential for use in transparent healthcare devices to monitor the vibrations transmitted from hand-held vibration tools and in a skin-attachable vocal sensor.

Graphene enhanced flexible piezoelectric transducers for dynamic strain measurement: from material preparation to application

“…In recent years, the flexible transducers have gained a great interest in a wide range of engineering fields, such as biomedicine [4][5][6], electronic skin [7,8], ultrasound diagnosis [9,10], and vibration detection [11][12][13], etc. These flexible devices with the capability for measuring dynamic strain open up a new way for SHM of complex structures because of its non-destructivity, sensitivity, high accuracy, and strong penetration capability.…”