Low-cost, μm-thick, tape-free electronic tattoo sensors with minimized motion and sweat artifacts

TLDR

Electronic tattoos are ultra‑thin, skin‑conformable devices for physiological sensing, but traditional fabrication is costly and the recent cut‑and‑paste approach, while cheaper, still relies on tape that thickens the device and reduces breathability. This work presents a slightly modified cut‑and‑paste method that produces low‑cost, open‑mesh e‑tattoos only 1.5 µm thick. The resulting ultra‑thin e‑tattoos can be directly pasted onto skin, conforming to its natural texture. We show that these tape‑free e‑tattoos accurately record ECG, skin temperature, and hydration, enabling extraction of heart and respiratory rates while minimizing motion artifacts and remaining unaffected by perspiration.

Abstract

Abstract Electronic tattoos (e-tattoos), also known as epidermal electronics, are ultra-thin and ultra-soft noninvasive but skin-conformable devices with capabilities including physiological sensing and transdermal stimulation and therapeutics. The fabrication of e-tattoos out of conventional inorganic electronic materials used to be tedious and expensive. Recently developed cut-and-paste method has significantly simplified the process and lowered the cost. However, existing cut-and-paste method entails a medical tape on which the electronic tattoo sensors should be pasted, which increases tattoo thickness and degrades its breathability. To address this problem, here we report a slightly modified cut-and-paste method to fabricate low-cost, open-mesh e-tattoos with a total thickness of just 1.5 μm. E-tattoos of such thinness can be directly pasted on human skin and conforms to natural skin texture. We demonstrate that this ultra-thin, tape-free e-tattoo can confidently measure electrocardiogram (ECG), skin temperature, and skin hydration. Heart rate and even respiratory rate can be extracted from the ECG signals. A special advantage of such ultra-thin e-tattoo is that it is capable of high-fidelity sensing with minimized motion artifacts under various body movements. Effects of perspiration are found to be insignificant due to the breathability of such e-tattoos.