Video-tactile pneumatic sensor for soft tissue elastic modulus estimation

Abstract

BackgroundA new sensor for estimating elasticity of soft tissues such as a liver was developed for minimally invasive surgery application.MethodsBy measuring deformation and adjusting internal pressure of the pneumatic sensor head, the sensor can be used to do palpation (indentation) of tissues with wide range of stiffness. A video camera installed within the sensor shell is used to register the radius of the contact area. Based on finite element model simulations and the measured data, elastic modulus of the indented soft tissue can be calculated.Results and conclusionsThree phantom materials, namely plastic, silicone and gelatin, with varied stiffness were tested. The experimental results demonstrated that the new sensor can obtain highly reliable data with error less than 5%. The new sensor might be served as an instrument in laparoscopic surgery for diagnosis of pathological tissues or internal organs.

Recent Advances in Robot-Assisted Surgery: Soft Tissue Contact Identification

“…Moreover, advanced tactile sensorization is currently under intensive research, e.g. using force sensor arrays, based on pressure measurement or optical phenomena [15], [16], [23], [31]- [33].…”

“…This technique involves several different types of image processing methods, such as feature extraction, filtering of light reflections, and also can be approached using neural networks, but the crucial parts are usually the reconstruction of the tissue surface and handling the inhomogenity in the tissue. Based on the detected deformations of the targeted tissue surface, the applied force values can be estimated [33], [61]- [63], [65]. Despite the mentioned benefits of this technique, the implementation is extremely complex, and usually computationally intense.…”

ESPRESS.0: Eustachian Tube-Inspired Tactile Sensor Exploiting Pneumatics for Range Extension and SenSitivity Tuning

“…It is, therefore, hard to achieve high quality results for a palpatory task involving unpredictable tactile stimuli that may exhibit a large range of stiffnesses when controlling only the force, position, and velocity of the sensor. Soft robotic sensors that can actively control their inner pneumatic pressure, and therefore their effective stiffness, shape, and friction coefficient have demonstrated utility in a number of tactile tasks including estimating bulk tissue elastic modulus [ 14 , 15 ], detecting the presence of an embedded stiff node in a soft material [ 16 ], and detecting and reacting to slip [ 17 , 18 ].…”

Optical-Tactile Sensor for Lump Detection Using Pneumatic Control

“…One such deviation proposed in literature comprises adjusting the effective stiffness of the soft tactile membrane via pneumatic actuation in order to allow for the sensitivity and measurement range of the sensor to be adjusted, leading to a more generically applicable sensor ( He et al, 2020a ; Jenkinson et al, 2020 ; Zhang et al, 2021 ). Previous studies exploring pneumatic actuation within soft tactile sensors have applied this to reactive grasping ( McInroe et al, 2018 ), shape identification ( Huang et al, 2019 ; Xiang et al, 2019 ), estimating tissue elastic modulus ( Gubenko et al, 2017 ) and an explorative capsule capable of self-locomotion ( Hinitt et al, 2015 ). Variable effective stiffness tactile sensors have also been applied to emulate nodules inside phantom organs to assist with medical diagnosis training ( He et al, 2020b ).…”