Cellular Polypropylene Piezoelectret for Human Body Energy Harvesting and Health Monitoring

Abstract

wileyonlinelibrary.comHowever, fragile inorganic piezoelectric materials, such as lead zirconate titanate (PZT) [ 16 ] and lead magnesio-niobate titanate (PMN-PT), [ 17 ] contain the lead element, which carries potential health risks. The piezoelectric property of fl exible organic piezoelectric materials, such as polyvinylidene fl uoride (PVDF), [ 18 ] is not excellent enough for practical applications. Traditional fl exible triboelectric generators and electrostatic generators go against to assemble with human body well. [20][21][22][23][24][25] Though, single electrode triboelectric generators are proposed to address the issue signifi cantly, the exposed residual charges of generators are easy to lose. [ 26,27 ] Consequently, new strategy should be proposed to develop other kind of fl exible generators to sustainably power the wearable electronic systems. Cellular polypropylene piezoelectret, which is fl exible, light-weight, inexpensive, and has the similar property with traditional piezoelectric materials, [28][29][30] was fi rst proposed by Kari Kirjavainen and co-workers in 1990. [ 31 ] In the past 25 years, cellular polypropylene has been applied in many transducer applications, like loudspeakers and energy harvesters, because of its rather small specifi c acoustic impedance and relative high piezoelectric coeffi cient ( d 33 ). [32][33][34][35] Herein, we present a new type of fl exible generator based on cellular polypropylene piezoelectret. By virtue of the outstanding mechanical property and high d 33 , the simple-structured cellular polypropylene piezoelectret fl exible generator (CPPFG) can effi ciently transfer the mechanical energy into electrical power and possesses long-term stable output performance, reaching the peak power density of ≈52.8 mW m −2 . For wearable and human interactive applications, self-powered human body biological signals detecting sensors that can sensitively measure the coughing action and arterial pulses were demonstrated, indicating the potential application in healthy monitoring. This study develops a new and effi cient path for human body energy harvesting and interactive sensing. Results and DiscussionThe fabrication process began with the low-cost and easy-gotten biaxially oriented multilayer polypropylene fi lm (Treofan fi lm EUH75). The detailed process is schematically provided in Figure 1 a. The multilayer polypropylene fi lm was fi rst put into a chamber with the chamber pressure of 2 MPa and temperature of 100 °C for 3 h, following by a quick defl ation process. Cellular Polypropylene Piezoelectret for Human Body Energy Harvesting and Health MonitoringNan Wu , Xiaofeng Cheng , Qize Zhong , Junwen Zhong , Wenbo Li , Bo Wang , Bin Hu , and Jun Zhou * Self-powered and wearable electronics, which are away from the problems of batteries, can provide the sustainable and comfortable interactive service for people. In this work, cellular polypropylene piezoelectret, which is with excellent physical and electrical properties, is utilized to build the human body energy ...

Monitoring of Vital Signs with Flexible and Wearable Medical Devices

“…[ 188 ] Flexible piezoelectric nanogenerators have recently been developed based on more fl exible forms of PZT such as thin ribbons [ 189 ] or nanowires, [ 190 ] as well as lead-free materials such as PVDF, [ 145,165,[191][192][193] ZnO nanowires, [ 194 ] and cellular polypropylene. [ 75 ] Triboelectric generators, on the other hand, generate electricity from the transfer of surface charge that occurs when certain materials, including many common metals and polymers, are brought into contact, [ 144 ] either by pressing and releasing [ 195 ] or sliding. [ 196 ] Piezoelectric and triboelectric sensors have been used to harvest energy from the motion of joints such as wrists, fi ngers, elbows, and knees.…”

“…While some self-powered sensing elements have recently been developed, [ 19,66,67,75,115 ] most health monitoring devices require power to drive the sensing elements; examples include resistive strain and temperature sensing and optoelectronic measurements such as photoplethysmography. In addition to the demands of the sensor itself, power is required to analyze the data collected and to communicate or display the result.…”

“…Examples of self-powered sensors are the piezoelectric respiration and heart rate sensors, [ 66,75 ] triboelectric respiration and heart rate sensors, [ 67,115 ] and thermoelectric temperature sensors. [ 19 ] However, since requirements for data processing and communication are signifi cant, a system with a self-powered sensing element is not necessarily able to be fully self-powered.…”

“…[ 39,[70][71][72][73][74][75] These novel pressure sensors are typically in the form factor of capacitors, which use either a compressible dielectric to induce a change in capacitance or a piezoelectric dielectric to induce a voltage across the device. The signal from the capacitive elements are either amplifi ed by an external instrument or a monolithically integrated device on the same substrate, typically a thin fi lm transistor (TFT).…”

Self‐Powered Multimodal Temperature and Force Sensor Based‐On a Liquid Droplet

“…[1][2][3][4][5][6] Thed iversity of demand has inspired sensor devices based on many different mechanisms,i ncluding resistance sensors, [7][8][9] capacitive sensors, [10] piezoelectric sensors, [11][12][13] thermoelectric sensors, [14] and field-effect transistor (FET) devices. The deformation of the droplet and the temperature difference across the droplet can induce an alternating pulse voltage and adirect voltage,respectively,which is easy to separate/analyze and can be utilized to sense the external force and temperature simultaneously.Inaddition, an integral displaysystem that can derive information from external temperature/force concurrently is constructed.…”