fig2

Figure 2. Mechatronic design and performance characterization of the sensor. (A) Comparison of the neural-mechanical sensor and commercial gel electrode. Impedances are analyzed for the two electrodes adhered to the skin on the BIC; (B) EMG characterization for the two electrodes. The measured EMG captured by the neural-mechanical sensor and commercial gel electrode were compared in terms of SNRs; (C) Effect of muscle deformations on the impedance of the skin-electrode interface; (D) Impedance variation with cyclic compression. The maximum impedance change was only 1.05% with a cyclic loading for 750 times; (E) Mechanical properties of the polyurethane sponges. In comparison of polyurethane sponges with different pore sizes, the pore density of 60 PPI exhibited the highest sensitivity in the compression test; (F) Effects of CCTO on the sensitivity of muscle deformation measurements. The sensitivity of the sensor with CCTO is three times higher than that without CCTO; (G) Cyclic compression test. During 14,000 cycles of compression, the measured capacitive deformation exhibited a drift of approximate 0.85%; (H) SNR of the capacitive sensing for a tender touch. BIC: Biceps brachii; EMG: electromyography; SNRs: signal-to-noise ratios; PPI: par per inch; CCTO: copper calcium titanate.