Piezoelectric materials for flexible and wearable electronics: A review

Wu, Yongling; Ma, Yulin; Zheng, Hui; Ramakrishna, Seeram

doi:10.1016/j.matdes.2021.110164

Cited by 265 publications

(124 citation statements)

References 187 publications

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“…As shown in Figure 1 , there are mainly four different categories of sensing strategies for measuring electrophysiological signals, viz. piezoresistive [ 98 , 99 ], piezoelectric [ 100 , 101 , 102 , 103 ], iontronic [ 104 , 105 ], and capacitive [ 106 , 107 , 108 , 109 ]. Among them, the capacitive sensors possess several advantages, such as reusability, sterilization, and reduced leakage currents (eliminating the electrical short circuits between electrodes and biological tissues) [ 110 ].…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Stretchable and Wearable Capacitive Electrophysiological Sensors for Long-Term Health Monitoring

et al. 2022

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Over the past several years, wearable electrophysiological sensors with stretchability have received significant research attention because of their capability to continuously monitor electrophysiological signals from the human body with minimal body motion artifacts, long-term tracking, and comfort for real-time health monitoring. Among the four different sensors, i.e., piezoresistive, piezoelectric, iontronic, and capacitive, capacitive sensors are the most advantageous owing to their reusability, high durability, device sterilization ability, and minimum leakage currents between the electrode and the body to reduce the health risk arising from any short circuit. This review focuses on the development of wearable, flexible capacitive sensors for monitoring electrophysiological conditions, including the electrode materials and configuration, the sensing mechanisms, and the fabrication strategies. In addition, several design strategies of flexible/stretchable electrodes, body-to-electrode signal transduction, and measurements have been critically evaluated. We have also highlighted the gaps and opportunities needed for enhancing the suitability and practical applicability of wearable capacitive sensors. Finally, the potential applications, research challenges, and future research directions on stretchable and wearable capacitive sensors are outlined in this review.

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Section: Introductionmentioning

confidence: 99%

Recent Advances in Stretchable and Wearable Capacitive Electrophysiological Sensors for Long-Term Health Monitoring

et al. 2022

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“…has become a particularly important issue . It is worth noting that piezoelectric polymer materials featuring flexibility, processability, , and capability to convert mechanical energy in the environment into electricity is now drawing great attention in both the academic and industrial fields. , Piezoelectric polymeric materials feature an impressive nature to convert mechanical energy into electricity and offer promising application potential in future electronics, such as additional power source for portable electronics or self-powered sensors. , Nevertheless, most of the existing piezoelectric polymer materials are two-dimensional thin films, which cannot effectively utilize the strain concentration in the normal direction required by piezoelectric devices, and simultaneously, these films do not easily act as a structural material to bear stress in practical application environments . Therefore, great effort has been dedicated to develop the design and to fabricate three-dimensional polymer piezoelectric materials and devices …”

Section: Introductionmentioning

confidence: 99%

Toward Balanced Piezoelectric and Mechanical Performance: 3D Printed Polyvinylidene Fluoride/Carbon Nanotube Energy Harvester with Hierarchical Structure

Zheng

Song

et al. 2022

Ind. Eng. Chem. Res.

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With rapid consumption of fossil energy and its impact on the environment, the desire for clean energy is gradually increasing around the world, and piezoelectric polymers have received extensive attention owing to their capability to harvest discrete mechanical energy in the environment. However, the existing piezoelectric devices are mostly low-dimensional fibers or films, making it difficult to achieve a good balance between mechanical robustness and piezoelectric output. Herein, a polyvinylidene fluoride (PVDF)/multiwalled carbon nanotube (MWCNT) scaffold with a hierarchical porous structure and geometry was fabricated by chemical-foaming-assisted fused deposition modeling (FDM). Chemical foaming was triggered by the heat accompanied during FDM molding, where a microporous structure was formed inside the part without affecting the geometric design to realize strain accumulation in normal space. Moreover, the conductive MWCNT formed discontinuous and parallel morphology around the pores, which not only promotes the polling process and formation of electrets, but also avoids the electrical breakdown caused by the formation of the conductive network. Accordingly, the combined effect of hierarchical structure and incorporation of MWCNT leads to a balanced piezoelectric (open circuit voltage of 8.46 V and short circuit current of 157 nA) and mechanical performance (compressive modulus of 14.07 MPa). These excellent properties all demonstrate the potential capabilities of the developed piezoelectric nanogenerators in the field of self-powered nanosensors and portable devices.

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“…Among these devices, exible pressure sensors play a very important role in health monitoring by detecting blood pressure and heartbeat, which indicate human health conditions [10]. Based on their working mechanism, the pressure sensors generally are categorized into four types; piezoresistive [11][12][13][14][15], capacitive [16,17], piezoelectric [18,19], and triboelectric [20,21] types. Among them, the piezoresistive-type pressure sensors, which employ variations in contact area between electrodes and detect resistance changes under applied pressure, have many advantages such as high sensitivity, simple device structure, and easy read-out circuit [10,11].…”

Section: Introductionmentioning

confidence: 99%

3D-printing-assisted flexible pressure sensor with concentric circles patterns and high sensitivity for health monitoring

2022

Preprint

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In this study, the flexible pressure sensor is fabricated using polydimethylsiloxane (PDMS) with concentric circles pattern (CCP) through a fused deposition modeling (FDM)-type three-dimensional (3D) printer, and poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) as the active layer. Through layer-by-layer additive manufacturing, the CCP surface is generated from a thin cone model with rough surfaces by the FDM-type 3D printer. A novel compression method is employed to convert the cone shape to planar microstructure over glass transition temperature of polylactic acid (PLA) filament. To endow the CCP surface, PDMS is replicated by compressed PLA with conductivity and the PEDOT: PSS is coated by drop-casting. The size of CCPs are controlled by changing printing layer height (PLH), which is one of the 3D printing parameters. Sensitivity enhances as the PLH increases, and the pressure sensor with 0.16-mm PLH exhibits outstanding sensitivity (160 kPa− 1), corresponding linear pressure range (0-0.577 kPa) with good linearity of (R2 = 0.978), compared to other PLHs. This pressure sensor exhibited stable and repeatable operation under various pressures and durability under 4.7 kPa for 2000 cycles. Finally, various health signal motions such as wrist pulse signals, swallowing, and pronunciation of words were demonstrated as an application. These results support the simple fabrication of high sensitive, flexible pressure sensor for human health monitoring.

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Piezoelectric materials for flexible and wearable electronics: A review

Cited by 265 publications

References 187 publications

Recent Advances in Stretchable and Wearable Capacitive Electrophysiological Sensors for Long-Term Health Monitoring

Recent Advances in Stretchable and Wearable Capacitive Electrophysiological Sensors for Long-Term Health Monitoring

Toward Balanced Piezoelectric and Mechanical Performance: 3D Printed Polyvinylidene Fluoride/Carbon Nanotube Energy Harvester with Hierarchical Structure

3D-printing-assisted flexible pressure sensor with concentric circles patterns and high sensitivity for health monitoring

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