A Tissue‐Like Soft All‐Hydrogel Battery

Abstract

To develop wearable and implantable bioelectronics accommodating the dynamic and uneven biological tissues and reducing undesired immune responses, it is critical to adopt batteries with matched mechanical properties with tissues as power sources. However, the batteries available cannot reach the softness of tissues due to the high Young's moduli of components (e.g., metals, carbon materials, conductive polymers, or composite materials). The fabrication of tissue‐like soft batteries thus remains a challenge. Here, the first ultrasoft batteries totally based on hydrogels are reported. The ultrasoft batteries exhibit Young's moduli of 80 kPa, perfectly matching skin and organs (e.g., heart). The high specific capacities of 82 mAh g−1 in all‐hydrogel lithium‐ion batteries and 370 mAh g−1 in all‐hydrogel zinc‐ion batteries at a current density of 0.5 A g−1 are achieved. Both high stability and biocompatibility of the all‐hydrogel batteries have been demonstrated upon the applications of wearable and implantable. This work illuminates a pathway for designing power sources for wearable and implantable electronics with matched mechanical properties.

Biocompatible Conductive Hydrogels: Applications in the Field of Biomedicine

“…Hence, tissue-like soft batteries are of great significance for the development of biosensors. Ye et al [146] developed an integrated battery configuration with excellent electrical conductivity and high interfacial charge transfer efficiency based on self-developed CHs and formed a general approach to achieve ultrasoft batteries with high electrochemical performance (Figure 3f). At a current density of 0.5 A g −1 , the specific capacity of the lithium-ion battery based on self-developed CHs is 82 mAh g −1 , and the specific capacity of the zinc-ion battery is 370 mAh g −1 .…”

Rechargeable Micro‐Batteries for Wearable and Implantable Applications

“…[83,84] Thus, it is essential to fabricate tissue-matchable soft MBs for implantable applications. Zhang and coworkers [85] developed a new family of issue-like all-hydrogel soft aqueous Li-ion and Zn-ion MBs with only 80 kPa Young's moduli (Figure 7d), which should represent the first demonstration of all-hydrogel batteries. The resulting all-hydrogel MB and sensor integrated system could be tightly fitted to the heart surface and detected the strain changes caused by the heartbeat (Figure 7e).…”

“…Reproduced with permission. [ 85 ] Copyright 2021, Wiley‐VCH. f) Schematic of the process of fiber MB injecting into tissue via biofluid.…”

“…“All‐hydrogel aqueous MB”: Reproduced with permission. [ 85 ] Copyright 2021, Wiley‐VCH. “2D stacked K‐ion MB”: Reproduced with permission.…”

“…e) Real-time curves of the sensor's relative resistance and voltage changes under heart-beat. Reproduced with permission [85]. Copyright 2021, Wiley-VCH.…”