Gold Nanowire\nSponge Electrochemistry for Permeable\nWearable Sweat Analysis Comfortably and Wirelessly

Electrochemistry-based wearable and wireless sweat analysis\nis\nemerging as a promising noninvasive method for real-time health monitoring\nby tracking chemical and biological markers without the need for invasive\nblood sampling. It offers the potential to remotely monitor human\nsweat conditions in relation to metabolic health, stress, and electrolyte\nbalance, which have implications for athletes, patients with chronic\nconditions, and individuals for the early detection and management\nof health issues. The state-of-the-art mainstream technology is dominated\nby the concept of a wearable microfluidic chip, typically based on\nelastomeric PDMS. While outstanding sensing performance can be realized,\nthe design suffers from the poor permeability of PDMS, which could\ncause skin redness or irritation. Here, we introduce an omnidirectionally\npermeable, deformable, and wearable sweat analysis system based on\ngold nanowire sponges. We demonstrate the concept of all-in-one soft\nsponge electrochemistry, where the working, reference, and counter\nelectrodes and electrolytes are all integrated within the sponge matrix.\nThe intrinsic porosity of sponge in conjunction with vertically aligned\ngold nanowire electrodes gives rise to a high electrochemically active\nsurface area of ∼67 cm<sup>2</sup>. Remarkably, this all-in-one\nsponge-based electrochemical system exhibited stable performance under\na pressure of 10 kPa and 300% omnidirectional strain. The gold sponge\nbiosensing electrodes could be sandwiched between two biocompatible\nsweat pads, which can serve as natural sweat collection and outflow\nlayers. This naturally biocompatible and permeable platform can be\nintegrated with wireless communication circuits, leading to a wireless\nsweat analysis system for the real-time monitoring of glucose, lactate,\nand pH during exercise.