Integration designs toward new‐generation wearable energy supply‐sensor systems for real‐time health monitoring: A minireview

Abstract

Wearable sensing systems, as a spearhead of artificial intelligence, are playing increasingly important roles in many fields especially health monitoring. In order to achieve a better wearable experience, rationally integrating the two key components of sensing systems, that is, power supplies and sensors, has become a desperate requirement. However, limited by device designs and fabrication technologies, the current integrated sensing systems still face many great challenges, such as safety, miniaturization, mechanical stability, energy‐efficiency, sustainability, and comfortability. In this review, the key challenges and opportunities in the current development of integrated wearable sensing systems are summarized. By summarizing the typical configurations of diverse wearable power supplies, and recent advances concerning the integrated sensing systems driven by such power supplies, the representative integrated designs, and micro/nanofabrication technologies are highlighted. Lastly, some new directions and potential solutions aiming at the device‐level integration designs are outlooked.

Advanced Wearable Thermocells for Body Heat Harvesting

“…[1,2] In contrast to more traditional energy storage systems (e.g., batteries [3] and supercapacitors [4] ), which require manual recharging, flexible energy harvesters (including solar cells, [5] piezoelectric polymer generators, [6,7] triboelectric generators, [8,9] and thermoelectric generators [10][11][12][13] ) convert energy from the local environment, including mechanical motion or temperature gradients from the human body, to electrical charge. [14,15] These energy harvesters are environmentally friendly power sources, which potentially provide a pathway toward the elimination of manual device charging and a reduction in battery waste. [10] Among these power sources, thermoelectric generators (TEG) attached to the human body are highly attractive, as the heat continually being emitted by the body (up to 20 mW cm −2 ) enables a constant power supply, in contrast to motion-based, or solar-based energy harvesting technologies.…”

Screen-Printed Electrodes: Promising Paper and Wearable Transducers for (Bio)Sensing

“…In general, there are three different modes of integrating wearable biosensors and power supplies: (1) an external circuit connection which is bulky and cumbrous; (2) a flexible substrate-based integration; and (3) all-in-one integration [ 78 ]. The last two strategies, made possible by advances in device designs and micro/nanofabrication technologies, are more widely used.…”

“…Currently, wearable biodevices are powered mainly by (i) safe high energy wearable batteries; (ii) energy conversion devices (piezoelectric and triboelectric nanogenerators, which harvest the mechanical energy in human motions, such as walking, breathing, and waving arms; solar cells, which harness light energy; thermoelectric supercapacitors; biofuel; and water-voltage cells); (iii) energy storage devices (mechanically flexible energy storage elements, mainly supercapacitor, and lithium-ion battery); (iv) hybrid power supplies combining energy conversion with energy storage; and (v) wireless energy transfer (wireless coils, like RF antennas). Significant progress have also been made in self-power and energy-efficient or even energy-free systems devices, fueled by the development of high-efficiency energy acquisition approach and ultra-low power consumption technique [ 68 , 69 , 78 , 79 , 80 ].…”

Potentially Wearable Thermo‐Electrochemical Cells for Body Heat Harvesting: From Mechanism, Materials, Strategies to Applications

“…These self-powered systems use energy that is environmentally friendly and sustainable, with recent developments in advanced wearable energy conversion devices enabling efficient power extraction from users (especially the elderly). [20][21][22][23] For example, solar cells are widely applied, and show the greatest potential among energy conversion devices, with the latest advances surrounding flexible and stretchable solar cells. [15,24,25] The fast growth of piezoelectric and triboelectric generator devices, driven by improved mechanistic understanding, [26,27] has led to the emergence of self-powered systems via harvesting mechanical energy from the human movement.…”