Low-Cost Flexible Piezoelectric Sensors for Real-Time Tactile Monitoring and Energy Harvesting
Ritesh Kumar Singh, Monika Gadhewal, Mohd Saqib, Sourav Maity, Shree Prakash Tiwari
Abstract
This work presents comprehensive investigation and demonstration of flexible piezoelectric tactile sensors for IoT-enabled electronic skin (E-skin) applications. These sensors were fabricated using a solution-processed thin film of poly (vinylidene fluoride-trifluoro ethylene), i.e. P(VDF-TrFE) sandwiched between low cost copper (Cu)-cladded polyamide (PI) sheets, and exhibited extremely low response time < 20 ms for ultra-soft finger touch. Excellent sensitivity of ~1.34 V/N was extracted by measuring the finger tapping force, with high peak-to-peak output voltage (V<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P-P</sub>) response of ~6.2 V for a touch with force of ~4.5 N. E-skin functionality was investigated by attaching these sensors to various parts of body such as fingers, knee, hand, wrist, and neck. Maximum response for neck movement with VP-P value of 5.12 V was achieved. Real-time sensing of tactile activities was demonstrated through array of sensors integrated with IoT cloud. Moreover, excellent energy harvesting capabilities of these devices were verified by charging a 22 μF capacitor through a bridge rectifier circuit upon repeated finger tapping for 20 s to 1.2 V. Our investigations indicate that these solution-processed flexible tactile sensors can be useful for demonstration of IoT enabled self-powered flexible E-skin for robotics applications.