## 3 Results and Discussion
### Electrophysiology Measurement of the Human Body  
Biopotential monitoring from the human body (called \"electrophysiology\") provides direct evidence to determine a human body in a healthy state and diseased state. It can show a wide range of medical information about the patient [80, 81, 82]. Conventional electrodes used in electrophysiology are classified as wet and dry electrodes. As the gold standard, 3-M Ag/AgCl gel electrode is an example of a wet-type electrode that is commonly used owing to low-impedance contact with the skin, reduced noise due to motion artifacts of a subject or wiring, and being easily disposable [83, 84, 85]. However, the performance is not long-lasting due to the constant gel dehydration with time, which sometimes results in skin irritation or allergic reactions, making them unsuitable for long-term bio-signal monitoring [85]. We used Au-SEBS films as bio-signal-sensing electrodes for measuring these EMG and ECG signals. Although our electrode was used as a dry electrode without a conductive gel, it was capable of effectively detecting the bio-signal when measuring the EMG and ECG in a simple experimental setup (Figure 6a) and determined the electrode positioning (Figure 6b for EMG and Figure 6d for ECG).  
EMG show useful information about the skeletal muscles. Its activation was recorded by a form of electrical potentials produced by a contraction of specific muscles to which the electrode is attached. Motor unit action potential (MUAP) means a summation of the potentials evoked at several muscle fibers around the electrode [86]. From the neuromuscular junction, acetylcholine (ACh) combines to ACh receptors on muscle tissue to start the action potential through depolarization by the inflow of sodium ions. EMG electrodes can detect the contraction and relaxation of the muscles in real time. It is an important tool for developing a human-machine interface and neuroprosthesis [87, 88]. In Figure 6c, the surface EMG was measured by attaching the Au-SEBS electrode on the flexor digitorum superficialis [39, 40] of the right forearm (Figure 6c). The signals of two designated motions (grasping and releasing the one hand) were shown at each peak, but the difference of the two motion signals was not big, so it is suggested that the motion artifact was mixed in the EMG signals. The sensing signal scale (Y-axis scale) was not sufficient for other dry EMG electrodes using PEDOT:PSS [89] or silver electrodes [90]. However, for practical applications, it is still needed for external signal processing systems that are capable of the noise filtering.  
An ECG can give us the electrical activity of the heart (a heart rhythm) in daily life. It is a simple but useful clinic tool to monitor and diagnose cardiovascular diseases such as arrhythmia, angina, and myocardial infarction from abnormal cardiac signals [91, 92]. The ECG signal is analyzed by a distinct graph shape from the pulsing of the heart on the surface of the skin, mainly the left chest. Commonly, its distinct peaks are called P, Q, R, S, and T peaks [93]. In the heart, autorhythmic cells lead the heartbeat as the pacemaker. In the ECG signal, the P peak is correlated on atrial depolarization of the cardiac cellular membrane by the inflow of sodium ions caused by the sinus node. Next, the QRS complex peaks mean the activation of the ventricles and widely spread electrical signals. Finally, the T peak occurs after the repolarization of the cardiac cellular membrane by the outflow of calcium and potassium ions. Depolarization is often maintained over two hundred milliseconds [94]. During the ECG measurements, we monitored five distinct peaks, revealing that cardiac activation of the volunteers clearly appeared in our electrode (Figure 6e). The sensingsignal scale was comparable with the other dry ECG electrodes that were previously reported [95; 96; 97]. However, it showed only a basic characterization of the five peaks and needed to improve the performance for more precise cardiac diagnosis applications.