On-Body Piezoelectric Energy Harvesters through Innovative Designs and Conformable Structures

Abstract

Recent advancements in wearable technology have improved lifestyle and medical practices, enabling personalized care ranging from fitness tracking, to real-time health monitoring, to predictive sensing. Wearable devices serve as an interface between humans and technology; however, this integration is far from seamless. These devices face various limitations such as size, biocompatibility, and battery constraints wherein batteries are bulky, are expensive, and require regular replacement. On-body energy harvesting presents a promising alternative to battery power by utilizing the human body's continuous generation of energy. This review paper begins with an investigation of contemporary energy harvesting methods, with a deep focus on piezoelectricity. We then highlight the materials, configurations, and structures of such methods for self-powered devices. Here, we propose a novel combination of thin-film composites, kirigami patterns, and auxetic structures to lay the groundwork for an integrated piezoelectric system to monitor and sense. This approach has the potential to maximize energy output by amplifying the piezoelectric effect and manipulating the strain distribution. As a departure from bulky, rigid device design, we explore compositions and microfabrication processes for conformable energy harvesters. We conclude by discussing the limitations of these harvesters and future directions that expand upon current applications for wearable technology. Further exploration of materials, configurations, and structures introduce interdisciplinary applications for such integrated systems. Considering these factors can revolutionize the production and consumption of energy as wearable technology becomes increasingly prevalent in everyday life.

Technology Roadmap for Flexible Sensors

“…The mechanism is to convert macroscale stretching to localized bending and twisting, which are permitted by reduced thickness. Origami and kirigami employ similar concepts . Moreover, for relatively rigid substrates such as leather and polyimide, adding a strain-isolation layer with substantially lower modulus ( e.g.…”

Electronic Textile Sensors for Decoding Vital Body Signals: State‐of‐the‐Art Review on Characterizations and Recommendations

“…A similar discussion is warranted for other sensing modalities to identify the main confounding factors for in vivo measurement—interested readers are encouraged to explore the associated complexities of in vivo testing for other sensors including capacitive, inductive, triboelectric, and piezoelectric sensors discussed in recent articles. [ 41,67,72,181–184 ]…”

“…A similar discussion is warranted for other sensing modalities to identify the main confounding factors for in vivo measurement-interested readers are encouraged to explore the associated complexities of in vivo testing for other sensors including capacitive, inductive, triboelectric, and piezoelectric sensors discussed in recent articles. [41,67,72,[181][182][183][184] The smart textile sensor industry is young but has experienced unprecedented growth in recent years. The underlying motivation of our work is to introduce a protocol to ensure proper quality control of this young but vibrant industry.…”

MetaMembranes for the Sensitivity Enhancement of Wearable Piezoelectric MetaSensors

“…Transfer printing is one of the fabrication methods which enables a combination of materials with different properties onto flexible membranes. Moreover, 3D printing and 4D printing are other techniques that can be achieved through various additive manufacturing processes such as micro-stereolithography, multiphoton lithography, laser chemical vapor deposition (LCVD), laser-induced forward transfer (LIFT), and UV lithography [39,[49][50][51][52].…”

“…Khan et al [32] investigated the elastic, dielectric, and piezoelectric properties of hexagonal honeycomb for light-weight piezoelectric sensors and actuators. Very recently, metamaterial-based substrate (MetaSub) was introduced by Farhangdoust et al [4] for the power enhancement of piezoelectric energy harvesters in which the MetaSub design was made by a combination of uniaxial kirigami and hexagonal patterns to increase the planar stretchability of the sub- Although most of the substantial features of metamaterials have recently been studied for the strain-type of piezoelectric sensors and harvesters, the application of metamaterialinspired membranes (MetaMem) for inflatable and pressure sensors is still in the early research stage [39]. In a low-pressure regime, the low sensitivity output is an important challenge of conventional pressure sensors (CPSs) using capacitive and piezoresistive measurement principles [39].…”