Research ArticleMATERIALS SCIENCE

Hierarchically patterned self-powered sensors for multifunctional tactile sensing

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Science Advances  19 Aug 2020:
Vol. 6, no. 34, eabb9083
DOI: 10.1126/sciadv.abb9083
  • Fig. 1 Structure and working mechanism of the multifunctional sensor.

    (A) The sensor can be attached to a human finger, allowing multifunctional tactile sensing. Exploded-view schematic diagram shows that the sensor takes the form of a multilayer stack. (B) Photograph showing main components and the assembled sensor. (C) The SEM image of the prepared hydrophobic PTFE surface. (D) The SEM image of the prepared graphene/PDMS composite surface. (E) The SEM image of synthesized Ag NWs. (F) The simulated strain field (left) and electric potential (right) on the graphene/PDMS composite when the composites are subjected to the applied pressure and temperature gradient, respectively. (G) The electric potential on the PTFE when it is in contact with the object. Photo credit: Ya Yang, Beijing Institute of Nanoenergy and Nanosystems.

  • Fig. 2 Electric characterization of the sensor in response to pressure and temperature.

    (A) Schematic illustrations of the pressure and the measured mode of electrical signals. (B) The linear relation of the I-V curves illustrates the ohmic contacts between graphene/PDMS composite and Cu sheet electrodes. (C) The ΔI/Ioff first exhibits a sharp increase as function of a pressure below 4 kPa and then a small increase above 4 kPa. Error bars were calculated by five sets of data under each pressure. (D) Both the output current and external pressure on time kept well in step with the loading and unloading. (E) I-T curve exhibiting fast responsive and recovery times of <80 ms. (F) The current monotonically increases with the pressure. (G) Schematic illustrations of the temperature gradient and the measured mode of electrical signals. T0 is the ambient temperature, and Tc is the temperature of the object. (H) The linear relation of the I-V curves illustrates the constant shifting at various ΔT. (I) V-T curve exhibiting fast responsive and recovery times of <0.5 s. (J) Measured output voltage as a function of temperature gradient. (K) Measured temperature gradient curves of the graphene/PDMS composite. (L) Measured output voltage signals corresponding to the temperature gradient.

  • Fig. 3 Characterizing the performance of the TENG and identifying materials of objects from tactile-induced triboelectric signals.

    (A) Schematic illustrations of the TENG and the measured mode of electrical signals. (B) Output voltage signals of TENG for FEP (R = 100 megohms, d = 3 cm, frequency = 0.2 Hz). (C) Output voltage signals of TENG under different pressure values. (D) Output voltage signals of TENG illustrating the same values between 0.2 and 2 Hz. (E) The influence of gap distance for the TENG. (F) The influence of temperature for the TENG. (G) Output voltage signals of the TENG for five materials. (H) Enlarged curve of the signal for acrylic. (I) Enlarged curve of the signal for FEP. (J) Summarized peak amplitude. Data are means ± SEM. Error bars were calculated by five sets of data. (K) The two-factor material identification system. The system consists of the training process (1 to 3) and the identification process (4 to 9).

  • Fig. 4 Examples for the applications of sensors.

    (A) The sensor on a human finger showing the potential applications in wearable devices. (B) The infrared thermal image showing the temperature of the sensor. (C) Optical image showing the sensor controlling a water droplet for biomedical applications. (D) An optical image of a finger with the sensor touching a hot cup and a plot for the corresponding current change of the sensor. (E) Thermal image of a finger with the sensor touching a hot cup and a plot for the Vtherm responses of the sensor. (F) Images showing operations of the finger to contact with the cup and release. Plots show contact-induced electrification responses to a contact-release movement. Photo credit: Ya Yang, Beijing Institute of Nanoenergy and Nanosystems.

Supplementary Materials

  • Supplementary Materials

    Hierarchically patterned self-powered sensors for multifunctional tactile sensing

    Yang Wang, Heting Wu, Lin Xu, Hainan Zhang, Ya Yang, Zhong Lin Wang

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    • Sections S1 to S4
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