This paper presents a novel tactile sensing technique for tissue elasticity measurements. A prototype flexible tactile sensor has been successfully fabricated using polydimethylsiloxane as the structural material. The proposed sensor comprises an array of capacitors with no active elements used. By varying the sizes of sensing membranes within the capacitors, different stiffnesses of sensing diaphragms can be achieved. The elasticity of the targeted object can be thereafter measured based on the relative deflections of the sensing diaphragms. The fabricated sensor has been calibrated by an off-the-shelf polymer durometer hardness selector pack. The results show a sensing resolution of 0.1 MPa for elasticity measurement and a force sensing resolution as small as 5 mN. This flexible tactile sensor can be embedded on the distal portions of various endoscopic instruments for in vivo tissue elasticity measurements.
Bibliographical noteFunding Information:
Manuscript received June 2, 2009; revised August 3, 2009. First published November 13, 2009; current version published December 1, 2009. This work was supported in part by the Minimally Invasive Medical Technologies Center (MIMTeC), a National Science Foundation Industry–University Cooperative Research Center. Subject Editor S. Shoji.
The authors would like to thank Dr. H.-K. Lee for his prominent work on flexible tactile sensors and advice on sensor fabrication. Sensor fabrication and characterization were performed at the Nano-fabrication Center and the Characterization Facility at the University of Minnesota, Minneapolis, which are supported by the NSF’s National Nanotechnology Infrastructure Network.
- Capacitive sensor
- Polydimethylsiloxane (PDMS)
- Tactile sensor
- Tissue elasticity