Energy Harvesting Untethered Soft Electronic Devices

Abstract

Advances in wearable and stretchable electronic technologies have yielded a wide range of electronic devices that can be conformably worn by, or implanted in humans to measure physiological signals. Moreover, various cutting‐edge technologies for battery‐free electronic devices have led to advances in healthcare devices that can continuously measure long‐term biosignals for advanced human–machine interface and clinical diagnostics. This report presents the recent progress in battery‐less, wearable devices using a wide range of energy harvesting sources, such as electromagnetic energy, mechanical energy, and biofuels. Additionally, this report also discusses the principles and working mechanisms of near/far‐field communications, triboelectric, thermoelectric, and biofuel technologies.

Surface Wettability for Skin‐Interfaced Sensors and Devices

“…Compared with bulky diagnostic instruments or wrist-mounted wearables, the thin, soft, conformal sensors, and devices [1][2][3][4][5][6][7][8][9][10] can reliably interface with human skin [11][12][13][14] to provide biointegrated devices for health monitoring and disease diagnosis. [15][16][17] However, the practical applications of these skin-interfaced devices in long-term use have to consider device integrity and sensing performance variations [18] in varying hydrated conditions, including those from the ambient environment (outside) and the human body (inside) (Figure 1, top).…”

Tough and Healable Elastomers via Dynamic Integrated Moiety Comprising Covalent and Noncovalent Interactions

“…Elastomers with controlled compositions and mechanical performance offer an important platform to facilitate technological breakthroughs in the area of flexible electronics for advanced wearable sensors, − soft robotics, − and human–machine interface. − A widely used approach to integrating electronic devices relies on the deposition of active materials onto the surface of substrates. , Taking advantage of elastomers as a substrate has emerged as a promising strategy to fabricate flexible electronics with good conformity and attachment to curved surfaces. , Driven by the requirement of flexibility, conformity, and durability of the electronics, some commercially available elastomers have been incorporated into these electronics. − However, most commercially available elastomers, especially those with high toughness cannot restore their pristine mechanical performance after damage due to the irreversible cross-linked networks, leading to the failure of electronics and environmental pollution. To enhance the service life and reliability of flexible devices, the use of healable elastomers as a substrate has been regarded as a promising strategy. − …”

“…21,22 Taking advantage of elastomers as a substrate has emerged as a promising strategy to fabricate flexible electronics with good conformity and attachment to curved surfaces. 23,24 Driven by the requirement of flexibility, conformity, and durability of the electronics, some commercially available elastomers have been incorporated into these electronics. 25−29 However, most commercially available elastomers, especially those with high toughness cannot restore their pristine mechanical performance after damage due to the irreversible cross-linked networks, leading to the failure of electronics and environmental pollution.…”

Direct Writing of Functional Layer by Selective Laser Sintering of Nanoparticles for Emerging Applications: A Review

“…Emerging applications such as renewable energy devices [ 1 ], flexible/stretchable/wearable electronics [ 2 ] and soft robotics [ 3 ] are still at their development stages, and discovery of functional smart materials relevant to each application has played a critical role in the advancement of these fields. Introduction of new materials requires concurrent evolution of appropriate processing methods [ 4 , 5 ], discernable from conventional techniques, since the existing technologies are generally designed and optimized for a specific material, i.e., photolithography for silicon wafer, and therefore, are often not compatible with other materials such as chemically synthesized low-dimensional nanomaterials and polymer-based substrates [ 6 ].…”