## 4 Conclusions  
We fabricated soft bio-integrated multifunctional devices that can be attached to human skin to monitor and diagnose the health of a subject. Au-SEBS electrodes with varying thicknesses of the Au nanomembrane were prepared using the conventional evaporation process to investigate the effect of the thickness on the electrical properties of the sensor, such as the initial sheet resistance and electrical breakdown at the design stage. Furthermore, the morphological and mechanical analyses showed that the proposed sensors exhibited a stable low resistance under a strain based on the intrinsically stretchable conducting Au nanomembranes. After investigation, the selected Au-SEBS electrodes were used as strain sensors, electrochemical sensors, temperature sensors, heaters, and electrophysiological sensors (EMG and ECG). The proposed Au-SEBS electrode-based sensors exhibited comparable performances to the previously reported wearable sensor devices and can be potential candidates for applications in wearable biomedical devices. If combined with signal processing systems, we expect that our Au-SEBS electrode can be widely applicable in the healthcare industry, such as when using the Internet of Things technology and deep neural networks in developing personal healthcare and diagnosis systems in the future. The following are available online at [[https://www.mdpi.com/article/10.3390/app11146562/s1](https://www.mdpi.com/article/10.3390/app11146562/s1)]([https://www.mdpi.com/article/10.3390/app11146562/s1](https://www.mdpi.com/article/10.3390/app11146562/s1)): Figure S1: Scanning electron microscope images of Au-SEBS electrodes with designated thickness. Figure S2. (a) Simple working principal diagram of the proposed Au nanomembrane strain sensor. (b) Diagram of the Au nanomembrane strain sensor without a crack. (c) Diagram of the Au nanomembrane strain sensor elongated \(\sim\)100%. (d) Diagram of the Au nanomembrane strain sensor elongated below the fracture strain. (e) Diagram of the Au nanomembrane strain sensor elongated above the fracture strain. Figure S3. Optical images of the Au nanomembrane of a 50-nm Au thickness when stretched 300% at the motorized X-translation stage. **Author Contributions:** S.L. designed and fabricated the stretchable polymer/Au nanomembrane sensor. K.K. performed the quantitative and qualitative experiments. Methodology, H.C. and J.Y. ; validation, Y.K. ; formal analysis, S.A.; investigation, H.J. ; resources, D.S. ([PERSON]); data curation, K.P. ; supervision, H.B. and D.S. ([PERSON]); and project administration, H.B. and D.S. ([PERSON]). All authors have read and agreed to the published version of the manuscript. Figure 6: (a) Electrophysiology measurement setup. (b) Electrode positioning for EMG measurements. (c) EMG signals acquired from the forearm skin when the volunteer performed two hand gestures (grasping and releasing). (d) Electrode positioning for the ECG measurements. (e) ECG signals acquired from the volunteer’s body. Several alphabetic captions expressed the cardiac signal state (PQRST peaks). **Funding:** This research was funded by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2020R1C1C1005567) and the Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Korean government (MSIT) (No. S-2020-1443-000). This research was also supported by a ICT Creative Consilience program (IITP-2020-0-01821) supervised by the IITP (Institute for Information & Communications Technology Planning & Evaluation), a SMC-SKKU Future Convergence Research Program grant and a Korea Medical Device Development Fund grant funded by the Korean government (the Ministry of Science and ICT, the Ministry of Trade, Industry and Energy, the Ministry of Health & Welfare, and the Ministry of Food and Drug Safety) (Project No: 202012D28). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.