Design, Modeling and Simulation of a Micro Tactile Sensor for Soft Tissue Stiffness Measurement with Three Tips Configuration

2015 ◽  
Author(s):  
Ahmed Fouly ◽  
Mohamed N. A. Nasr ◽  
Ahmed M. R. Fath El Bab ◽  
A. A. Abouelsoud
Keyword(s):  
Soft Tissue ◽  
Modeling And Simulation ◽  
Tactile Sensor ◽  
Tissue Stiffness ◽  
Stiffness Measurement

Design and Simulation of Micro Tactile Sensor for Stiffness Detection of Soft Tissue with Irregular Surface

2020 ◽  
Vol 18 (3) ◽  
pp. 200-209
Author(s):  
Ahmed Fouly ◽  
Ahmed M. R. FathEl-Bab ◽  
A. A. Abouelsoud ◽  
T. Tsuchiya ◽  
O. Tabata
Keyword(s):  
Soft Tissue ◽  
Soft Tissues ◽  
Tactile Sensor ◽  
Sensor Output ◽  
Irregular Surface ◽  
Tissue Stiffness ◽  
Tactile Sensors ◽  
Element Analysis ◽  
Detailed Design ◽  
Sensor Structure

Tactile sensors become an essential part of many applications in our life. Integrating tactile sensors with surgical tools used in MIS is significant to compensate for the shortage of touch feeling of soft tissues and organs comparing with traditional surgeries. This paper presents a detailed design of a micro tactile sensor for measuring the stiffness of soft tissue with an irregular surface. The sensor consists of five cantilever springs with different stiffness. A spring in the middle has a relatively low stiffness surrounded by 4 springs have relatively equal high stiffness to compensate for the soft tissue contact error in the longitudinal and lateral directions. Sensor parameters are selected to ensure high sensitivity and linearity with taking into consideration the cross-talk effect among the sensor springs tips. A detailed design of the sensor structure in the microscale is conducted based on some constraints related to MEMS fabrication. A finite element analysis (FEA) of the sensor structure is conducted to evaluate sensor structure performance using CoventorWare software. Then, an FEA for the piezo-resistors, as a signal transduction method, is conducted which maps the sensor output to an electrical signal. The results prove that the sensor can differentiate among different soft-tissue stiffness within the selected range independent of the applied distance between the sensor and the tissue with an error below 3% even with inclination angle between the sensor and the tissue ±3°. Furthermore, a linear performance has been achieved between the soft-tissue stiffness and the sensor output.

scholarly journals Micro machined tactile sensor for soft tissue compliance detection

2009 ◽  
Vol 1 (1) ◽  
pp. 84-87 ◽  
Author(s):  
A.M.R. Fath El Bab ◽  
K. Sugano ◽  
T. Tsuchiya ◽  
O. Tabata ◽  
M.E.H. Eltaib ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Tactile Sensor ◽  
Tissue Compliance

scholarly journals A Piezoelectric Tactile Sensor for Tissue Stiffness Detection with Arbitrary Contact Angle

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6607
Author(s):  
Yingxuan Zhang ◽  
Feng Ju ◽  
Xiaoyong Wei ◽  
Dan Wang ◽  
Yaoyao Wang
Keyword(s):  
Contact Angle ◽  
Recognition Rate ◽  
Tactile Sensor ◽  
Normal Direction ◽  
Surgical Instruments ◽  
Tissue Stiffness ◽  
Design And Optimization ◽  
Detection Model ◽  
Sensor Optimization ◽  
Simulation And Experiment

In this paper, a piezoelectric tactile sensor for detecting tissue stiffness in robot-assisted minimally invasive surgery (RMIS) is proposed. It can detect the stiffness not only when the probe is normal to the tissue surface, but also when there is a contact angle between the probe and normal direction. It solves the problem that existing sensors can only detect in the normal direction to ensure accuracy when the degree of freedom (DOF) of surgical instruments is limited. The proposed senor can distinguish samples with different stiffness and recognize lump from normal tissue effectively when the contact angle varies within [0°, 45°]. These are achieved by establishing a new detection model and sensor optimization. It deduces the influence of contact angle on stiffness detection by sensor parameters design and optimization. The detection performance of the sensor is confirmed by simulation and experiment. Five samples with different stiffness (including lump and normal samples with close stiffness) are used. Through blind recognition test in simulation, the recognition rate is 100% when the contact angle is randomly selected within 30°, 94.1% within 45°, which is 38.7% higher than the unoptimized sensor. Through blind classification test and automatic k-means clustering in experiment, the correct rate is 92% when the contact angle is randomly selected within 45°. We can get the proposed sensor can easily recognize samples with different stiffness with high accuracy which has broad application prospects in the medical field.

A resonant tactile stiffness sensor for lump localization in robot-assisted minimally invasive surgery

2019 ◽  
Vol 233 (9) ◽  
pp. 909-920
Author(s):  
Yahui Yun ◽  
Yaming Wang ◽  
Hao Guo ◽  
Yaoyao Wang ◽  
Hongtao Wu ◽  
...  
Keyword(s):  
Minimally Invasive Surgery ◽  
Theoretical Model ◽  
Minimally Invasive ◽  
Resonant Frequency ◽  
Frequency Shift ◽  
Invasive Surgery ◽  
Tactile Sensor ◽  
Tissue Stiffness ◽  
Robot Assisted ◽  
Resonant Frequency Shift

A miniature resonant tactile sensor for tissue stiffness detection in robot-assisted minimally invasive surgery is proposed in this article. The proposed tactile sensor can detect tissue stiffness based on the principle of the resonant frequency shift when it contacts with tissue of different stiffness. A PZT (lead zirconate titanate) bimorph works simultaneously as the actuator and the sensing element, which is helpful for simplifying the structure. The resonant frequency shift can be deduced by measuring the electrical impedance of the PZT bimorph, since there will be an abrupt change of the impedance when resonance occurs. A unique structure of an Archimedean spiral metal sheet is introduced to restrict the outer size of the sensor within 10 mm and to keep the resonant frequency low. A theoretical model is established. Finite element method analyses are carried out to validate the working principle and it meets the theoretical model quite well. Several silicone samples are tested with the sensor and the results show that the proposed sensor is capable of measuring tissue stiffness within the range of 0–2 MPa, detecting and locating lumps inside tissue.

The Force Attenuation Provided by Hip Protectors Depends on Impact Velocity, Pelvic Size, and Soft Tissue Stiffness

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Andrew C. Laing ◽  
Stephen N. Robinovitch
Keyword(s):  
Soft Tissue ◽  
Impact Velocity ◽  
High Velocity ◽  
Rank Order ◽  
Tissue Stiffness ◽  
Surface Geometry ◽  
Hip Protectors ◽  
Soft Shell ◽  
Testing Standards ◽  
Pelvic Size

Wearable hip protectors represent a promising strategy for preventing hip fractures. However, there is lack of agreement on biomechanical testing standards and subsequent uncertainty about the ability of hip protectors to attenuate impact force during a fall. To address this issue, we designed a fall impact simulator that incorporated a “biofidelic” surrogate pelvis, which matched the surface geometry and soft tissue stiffness measured in elderly women (n=15). We then used this system to measure the attenuation in peak femoral neck force provided by two commercially available soft shell protectors (Safehip Soft and Hipsaver) and one rigid shell protector (Safehip Classic). Finally, we examined how the force attenuation provided by each protector was influenced by systematic changes in fall severity (impact velocity), body size (pelvis size), and soft tissue stiffness. With the biofidelic pelvis, the force attenuation averaged over all impact velocities was 27% for Safehip Soft, 17% for Safehip Classic, and 19% for Hipsaver. However, the rank order of hip protectors (and especially the performance of Safehip Classic) varied with the test conditions. Safehip Classic attenuated force by 33% during a low velocity (1m∕s) fall, but only by 8% for a high velocity (4m∕s) fall. In the latter condition, improved attenuation was provided by the soft shell hip protectors (19% by Safehip Soft and 21% by Hipsaver). As soft tissue stiffness increased from softest to most rigid, the attenuation provided by Safehip Classic increased 2.9-fold (from 26% to 76%), while Safehip Soft increased 1.7-fold (from 36% to 60%) and Hipsaver increased 1.1-fold (from 36% to 38%). As pelvis size decreased from largest to smallest, the attenuation provided by Safehip Classic increased 8-fold, but for a high velocity fall and moderate tissue stiffness, never exceeded that provided by Safehip Soft and Hipsaver. Our results indicate that, under biofidelic testing conditions, the soft shell hip protectors we examined generally provided greater force attenuation (averaging up to 27%) than the hard shell protector. Measured values of force attenuation were highly sensitive to variations in impact velocity, pelvic size, and pelvic soft tissue stiffness. This indicates the need to develop international testing standards to guide market approval, the selection of protectors for clinical trials, and the design of improved hip protectors.

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