Directional Sweat Transport and Breathable Sandwiched Electrodes for Electrocardiogram Monitoring System

Abstract

Device–body interface is significant for acquiring high quality bio‐signals, preventing skin‐irritation, and minimizing the motion artifacts. However, low breathability of the typical substrate used in a flexible electronic device usually deteriorates the stability of device–body interface, which is imperative for long‐term application but commonly disregarded. In paper, a directional sweat transport and breathable electrode with three‐layer sandwiched structure is reported. The top hydrophilic hydrolyzed‐polyacrylonitrile (HPAN) layer and middle hydrophobic thermoplastic‐polyurethane (TPU) layer form Janus structure; and the bottom layer is an electrode layer of Ag nanowires (AgNWs). This dedicatedly designed electrode can transport sweat from skin to the top HPAN layer, while keeping low noise electrocardiogram (ECG) signal detection. In the trial of ECG monitoring, the results show that the electrode can achieve reliable recording with high signal noise rate (SNR) both in calm state (10.5 dB) and sweaty state (10.1 dB) with sweat tolerance. No allergy or obvious SNR degeneration is observed when utilizing the electrode owing to the effective sweat transport away from the device–body interface rather than accumulation. Finally, the application of the anti‐sweat accumulating electrode in wearable electronics is demonstrated.

Skin bioelectronics towards long-term, continuous health monitoring

“…222 Additionally, the specialised design of fibre mats can guide the direction of sweat transport, thus maintaining the electrical performance of the skin-attached devices. 223,224 In addition to porous materials, film-type electronics have also been investigated. 225 Reeder et al developed waterproof, epidermal, microfluidic and electronic systems that adhere to the human skin for sweat collection, biomarker analysis, and thermography, even in aquatic settings.…”

Gas‐Permeable Organic Electrochemical Transistor Embedded with a Porous Solid‐State Polymer Electrolyte as an on‐Skin Active Electrode for Electrophysiological Signal Acquisition

“…Clear PQRST waveforms were also observed and the SNR was calculated to be 29.0 dB, which is comparable with or higher than those using the active electrodes [ 12,25 ] and higher than those using the passive electrodes. [ 40,41 ] From the results, we can see that the RH level on the skin surface satisfies the requirements of the OECT device. The ECG signals were simultaneously acquired and amplified using the OECT as the active electrode.…”

Bioinspired Perspiration‐Wicking Electronic Skins for Comfortable and Reliable Multimodal Health Monitoring

“…At the same time, these Au nanoparticles on the TPU surface are able to increase the roughness and thus hydrophobility of TPU fibers (Figure S5, Supporting Information). [22] Therefore, a surface energy gradient is constructed from the more hydrophobic Au-coated TPU layer to the less hydrophobic TPU layer and then to the hydrophilic CM layer. The dual function of the porosity gradient and surface energy gradient provides a strong driving force for the sweat transport, as will be discussed later.…”