| Summary: | 博士 === 國立成功大學 === 電機工程學系 === 102 === Bio-potential measurement in homecare and during long-term monitoring has recently received widespread attention. The purpose of this technology is to enable patients with chronic diseases to receive homecare or care close to home. However, commercial bio-potential electrodes are almost wet all electrodes (Ag/AgCl), and the drawback of wet electrodes is that they can cause itchiness, reddening, and swelling of the skin during long-term use. In recent years, researchers have begun to use micro-electro-mechanical systems (MEMS) technology to fabricate micro-needle dry electrodes and polymer dry electrodes. However, the literatures reporting these electrodes have some defects. For instance, an invasive micro-needle electrode could cause skin irritation; the wire connection of the polymer dry electrode offers a weak interface attachment, and the Au could flake off slightly.
The primary purpose of this study is to purpose an innovative flexible polydimethylsiloxane dry electrode (FPDE). The bio-compatible polydimethylsiloxane (PDMS) was made by using a polymethylmethacrylate (PMMA) material, a CO2 laser and a replica molding technique for FPDE structure building, and the novel FPDE uses bio-compatible Au as the skin contact layer, which is also made using the same technology. Furthermore, this work proposes a novel method to improve the PDMS surface roughness from nm to μm scale that increases Au adhesion strength on the PDMS surface by using a CO2 laser and a replica molding method. This method is unlike the literatures describing the use of O2 plasma etching and techniques using parylene-C. The study provides a novel FPDE concept where the super-hydrophobic effect is combined with a three-dimensional (3D) structure FPDE for bio-potential applications. The purpose of the super-hydrophobic effect is similar to that of a lotus leaf on the FPDE surface and offers good waterproofing property and reduces interference from the human body. The 3D FPDE with soft conical structures can fit the scalp surface even if it is hairy and provides low contact impedance for bio-potential application.
This work proposed a novel FPDE that could not easily cause itchiness, reddening, and swelling of the skin during long-term use as compared with standard wet electrodes. It also provides better reliability and a more robust attachment for a measurement method as compared to flexible polymer dry electrodes. Furthermore, the FPDE was integrated and packaged with a flexible and transparent PDMS covered with a three-pad FPDE into a novel one-point, wearable, wireless ECG acquisition device. The laser treatment method can increase the adhesion ratio by up to 57% (max.). The 3D FPDE can contact the skin through hair, which reduces impedance by 10% as compared with standard wet electrodes on hairy sites, and the value of the contact angle (154˚) achieves a super-hydrophobic effect similar to that of a lotus leaf.
This work proposed three types of FPDE design that can be integrated with bio-potential acquisition devices for single or multiple position bio-potential measurement. Importantly, the proposed FPDE can offer comfortable skin contact that improves the ease of medical care provided during homecare.
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