fig4
Figure 4. (A) A wide-bandwidth nanocomposite-sensor integrated smart mask for tracking multiphase respiratory activities[23]; (B) A smart ultrathin pressure sensor-based face mask for breath monitoring[28]; (C) An electronic tattoo for sensing multiple signals[43]; (D) Epidermal electronics for respiration monitoring[67]; (E) A wearable cardiac ultrasound imager[91].