Fig. 4: Various applications of VGS.
From: Vertical graphene on flexible substrate, overcoming limits of crack-based resistive strain sensors
a Snapshots of four LEDs that indicate the resistance level from low resistance (all lit) to overload (all off). A series of blinking LEDs operates stably even after the breakage status. b Operational block diagram for the wearable system operation. c Relative resistance variation for VGS under different bending angles. Insets show the bending angles of the index finger. d Image of the wearable system integrated with strain sensor for real-time finger bending monitoring. A Bluetooth transmitter sends sensor measurements for real-time data readout and logging on a tablet. e Relative resistance variation of VGS attached to a loudspeaker playing classical music (Ludwig van Beethoven Symphony No.5 in C minor, Op. 67 ‘Fate’: Allegro con brio). f Photograph of a wireless VGS conformally attached onto a tester’s throat for timbre recognition recording. g Comparison of the relative resistance variation during speech involving different languages and words, ‘A’, ‘B’, and ‘hello graphene’ in English, and ‘가 (ga)’, ‘나 (na)’, and ‘안녕 그래핀 (annyeong geulaepin)’ (with the same meaning) in Korean are repeated. All of the signals are recorded clearly and exhibit distinguishable phonation.
