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. 2022 Jan 7;8:705662. doi: 10.3389/frobt.2021.705662

FIGURE 2.

FIGURE 2

Electrical-based tactile sensors for MIS. (A–C) Piezoresistive tactile sensing. (A) Schematic and cross-sectional view of the piezoelectric tactile sensor consisting of two circular force sensing resistors with different diameters and one plastic filler plate, which can differentiate between the hardness of other types of elastomers (Kalantari et al., 2010). (B) Illustration of mechanical structure and a cross-sectional view for the individual three-dimensional force sensing cell of the tactile sensor (Mei et al., 2000). (C) 3D illustration and backside view of the bioinspired piezoelectric tactile sensor consisting of a silicone post on top of a bottom diaphragm with strain gauges (Hu et al., 2010). (D–F) Piezoelectric tactile sensing. (D) Schematic showing the structure and cross-sectional view of PVDF-based piezoelectric tactile sensor composed of three layers: a double-sided micromachined silicon plate, a PVDF film, and a Plexiglas support layer (Qasaimeh et al., 2008a). © 2008 IEEE. Reprinted, with permission. (E) The structural design of a PVDF-based sensor consisting of a rigid cylinder surrounded by a compliant cylinder for compliance measurement (Sedaghati et al., 2005). (F) Illustration of the triaxial tactile sensor employing an array of four active piezoelectric sensors (Lee et al., 2014). Copyright (2019) MDPI. (G–I) Capacitive tactile sensing. (G) Exploded view of the sensorized surgical forceps and the configuration of the 3-DOF capacitive force sensor under different applied forces showing the displacement between the sensing cells and the grounded part (Kim et al., 2018a). © 2018 IEEE. Reprinted, with permission. (H) Exploded view of the wrist force sensor and the electrode alignment of the three-axis capacitive force sensor at rest and under two applied forces (Lee et al., 2016). © 2016 IEEE. Reprinted, with permission. (I) Exploded view of the surgical palpation probe with the capacitance sensing PCB configuration and one case in which change in capacitance is generated by the capacitance sensing cells when Z-axis force is applied (Kim et al., 2018b). © 2018 IEEE. Reprinted, with permission.