1：Experimental Design and Method Selection:

The study involves a generic approach to treat commercial silver flakes with KI to iodize surfactants, followed by photo exposure to convert silver iodide to silver nanoparticles. This treatment is matrix-independent and aims to enhance conductivity by removing insulating surfactants and promoting sintering between flakes. ECCs are prepared by mixing treated flakes with various polymer matrices (e.g., PDMS, Ecoflex) and curing under optimized conditions.

2：Sample Selection and Data Sources:

Commercial silver flakes (SF-01C) are used as conductive fillers. Polymer matrices include silicone rubbers (Ecoflex 00-30, Sylgard 184, Silbione LSR 4305), isobutylene-isoprene rubber (IIR), styrene butadiene rubber (SBR), nitrile rubber (NBR), and butadiene rubber (BR). Human subjects are involved for electrophysiological signal measurements under ethical guidelines.

3：List of Experimental Equipment and Materials:

Equipment includes X-ray photoelectron spectrometer (Axis Ultra DLD), thermogravimetric analyzer (Shimadzu DTG-60H), Raman confocal microscope (LabRAM ARAMIS), field-emission scanning electron microscope (JEOL JSM-6701Fq), transmission electron microscope (JEM 2100 plus), four-point probe meter (Shanghai Qianfeng SB100A/2), solar simulator (Newport-Oriel Sol3A Class AAA, 94043A), LCR meter (E4980A, Keysight), data acquisition card (PXI-6289, National Instruments), and electronic universal testing machine (CMT-4304-QY). Materials include silver flakes (SF-01C), KI, various polymer matrices, and chemicals like ethanol and polyvinyl alcohol.

4：Experimental Procedures and Operational Workflow:

Silver flakes are treated by stirring with KI solution, cleaning, drying, and exposing to sunlight. Treated flakes are mixed with polymer matrices, applied to molds, and cured at optimized temperatures. ECCs are characterized for morphology, electrical properties, and performance in stretchable interconnects and on-skin electrodes. Electrophysiological signals (ECG, sEMG) are measured using fabricated electrodes and analyzed for human-machine interface applications.

5：Data Analysis Methods:

Electrical resistivity is measured using four-point probe and four-wire methods. Morphological analysis uses SEM, TEM, XPS, Raman spectroscopy, and TGA. Signal analysis for ECG and sEMG involves LabVIEW and Matlab for data acquisition and processing, including SNR calculation and gesture classification based on signal amplitude thresholds.