Flexible and multi-directional piezoelectric energy harvester for self-powered human motion sensor

Abstract

A flexible piezoelectric strain energy harvester that is responsive to multi-directional input forces produced by various human motions is proposed. The structure of the harvester, which includes a polydimethylsiloxane (PDMS) bump, facilitates the effective conversion of strain energy, produced by input forces applied in random directions, into electrical energy. The structural design of the PDMS bump and frame as well as the slits in the piezoelectric polyvinylidene fluoride (PVDF) film provide mechanical flexibility and enhance the strain induced in the PVDF film under input forces applied at various angles. The amount and direction of the strain induced in PVDF can be changed by the direction of the applied force; thus, the generated output power can be varied. The measured maximum output peak voltage is 1.75, 1.29, and 0.98 V when an input force of 4 N (2 Hz) is applied at angles of 0°, 45°, and 90°, and the corresponding maximum output power is 0.064, 0.026, and 0.02 μW, respectively. Moreover, the harvester stably generates output voltage over 1.4 × 104 cycles. Thus, the proposed harvester successfully identifies and converts strain energy produced by multi-directional input forces by various human motions into electrical energy. We demonstrate the potential utility of the proposed flexible energy harvester as a self-powered human motion sensor for wireless healthcare systems.

Multi‐Layered, Hierarchical Fabric‐Based Tactile Sensors with High Sensitivity and Linearity in Ultrawide Pressure Range

“…Thus, considerable progress has been made in the development of tactile sensors based on various sensing mechanisms, materials, and designs . Sensing mechanisms of the tactile sensors are mainly classified as resistive, capacitive, piezoelectric, or triboelectric types. Among these types, resistive sensors, which transduce applied pressure into a corresponding change in resistance, have been widely used due to their simple measurement scheme and relatively high reliability .…”

Nanogenerator-Based Self-Powered Sensors for Wearable and Implantable Electronics

“…PVDF is one kind of organic piezoelectric material and could also be used for fabricating PENG. The prepared device was composed by some slits in PVDF film and a polydimethylsiloxane (PDMS) bump, which could respond to multidirectional forces and convert strain energy [63]. As directions of the induced strain generating in PVDF varied with the changed direction of imposed force, the output generated became different.…”

A Review on Mechanisms for Piezoelectric-Based Energy Harvesters

“…In the past several decades, generating energy from the motion of humans [190][191][192], animals [193][194][195] and plants [196,197] has been of great interest for many researchers. Due to the development of this technology, the charging of mobile micro or nanoelectronics is of great ease [198,199].…”

“…Kim analyzed the effect of force (4N) and frequency (2 Hz) on output power for human-based piezoelectric energy harvesters at different angles (i.e., 0 • , 45 • , and 90 • ). The output maximum power obtained was 0.064, 0.026, and 0.02 µW, respectively [192]. Bai performed experimentation and numerical solution to harvest energy from a piezoelectric wrist band; output RMS power obtained from movement of human wrist was 50 µW [223].…”