Soft Liquid Metal-Based Conducting Composite with Robust Electrical Durability for a Wearable Electrocardiogram Sensor

Yewon Kim; Jihyang Song; Soojung An; Mikyung Shin; Donghee Son

doi:10.3390/polym14163409

Soft Liquid Metal-Based Conducting Composite with Robust Electrical Durability for a Wearable Electrocardiogram Sensor

Polymers (Basel). 2022 Aug 20;14(16):3409. doi: 10.3390/polym14163409.

Authors

Yewon Kim^{1

2}, Jihyang Song^{2

3}, Soojung An^{1

2}, Mikyung Shin^{2

4

5}, Donghee Son^{1

2

3}

Affiliations

¹ Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Korea.
² Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon 16419, Korea.
³ Department of Superintelligence Engineering, Sungkyunkwan University, Suwon 16419, Korea.
⁴ Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon 16419, Korea.
⁵ Department of Biomedical Engineering, Sungkyunkwan University, Suwon 16419, Korea.

Abstract

Liquid metals not only have the electrical property of conductivity, but they also have a unique characteristic of existing in a liquid state at room temperature, unlike ordinary stiff solid metals. However, in bioelectronics, the modulus matching well between a device and skin or tissue is considered very advantageous, because high-quality biological signals can be recorded. Therefore, it is possible to implement soft electronics with stable and robust electrical characteristics by using LM as a conductive liquid-state filler. In this study, we changed a type of liquid metal, Eutectic Gallium Indium (EGaIn), into a particle form via tip sonication and mixed it with a solution that dissolved Styrene-Ethylene-Butylene-Styrene (SEBS) in toluene to fabricate a composite. The EGaIn-SEBS composite has high conductivity, excellent electrical durability under mechanically harsh conditions, and a degree of modulus similar to that of bare SEBS, which is lower than that of solid-filler-based SEBS composite. Finally, we demonstrated electrocardiogram signal monitoring using an EGaIn-Alginate two-layer electrode (EATE) that was fabricated by simply coating the surface of the composite with alginate hydrogel, which demonstrates excellent performance in bioelectronics.

Keywords: composite; electrical durability; liquid metal; soft electronics; wearable device.

Grants and funding

This research was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (Nos. 2020R1C1C1005567 (D.S.), 2020R1C1C1003903 (M.S.) and 2022M3E5E9018583). This research was also funded by a Korea Medical Device Development Fund grant funded by the Korean government (the Ministry of Science and ICT, Ministry of Trade, Industry and Energy, Ministry of Health & Welfare, and Ministry of Food and Drug Safety) (No. 202012D28), an Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Korean government (MSIT) (No. 2020-0-00261, Development of low power/low delay/self-power suppliable RF simultaneous information and power transfer system and stretchable electronic epineurium for wireless nerve bypass implementation), and MSIT (Ministry of Science and ICT), Korea, under the ICT Creative Consilience program (IITP-2020-0-01821) supervised by the IITP (Institute for Information & Communications Technology Planning & Evaluation). This research was supported by the Institute for Basic Science (IBS-R015-D1). This research was supported by the National R&D Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (No. 2020M3H2A1076786). This research was supported by an SMC-SKKU Future Convergence Research Program Grant.