This paper presents a multi-axis low-cost soft magnetic tactile sensor with a high force range for force feedback in robotic surgical systems. The proposed sensor is designed to fully decouple the output response for normal, shear and angular forces. The proposed sensor is fabricated using rapid prototyping techniques and utilizes Neodymium magnets embedded in an elastomer over Hall sensors such that their displacement produces a voltage change that can be used to calculate the applied force. The initial spacing between the magnets and the Hall sensors is optimized to achieve a large displacement range using finite element method (FEM) simulations. The experimental characterization of the proposed sensor is performed for applied force in normal, shear and 45° angular direction. The force sensitivity of the proposed sensor in normal, shear and angular directions is 16 mV/N, 30 mV/N and 81 mV/N, respectively, with minimum mechanical crosstalk. The force range for the normal, shear and angular direction is obtained as 0–20 N, 0–3.5 N and 0–1.5 N, respectively. The proposed sensor shows a perfectly linear behavior and a low hysteresis error of 8.3%, making it suitable for tactile sensing and biomedical applications. The effect of the material properties of the elastomer on force ranges and sensitivity values of the proposed sensor is also discussed.

This paper presents the design of a multi-axis capacitive tactile force sensor with a fully decoupled output response for input normal and shear forces. A patterned elastomer is used as a dielectric layer between capacitive electrodes of the sensor that allows to achieve relatively higher sensitivity. The sensor is fabricated utilizing a low-cost rapid prototyping technique and is characterized for normal and shear forces in the range of 0 ~ 10 N and 0 ~ 3.1 N respectively. The achieved force sensitivity for the normal axis is 2.03%/N and for shear axes is 1.67%/N. The difference between the estimated force from the sensor and actual force applied is negligible, which demonstrates the accuracy of the sensor. The reliability of the sensor is analysed by performing hysteresis and repeatability tests. The hysteresis error is found to be 4.94% and 4.69% for normal and shear forces respectively. The repeatability error of the sensor is less than 5%, which shows the stability of the sensor. The high sensitivity, linear output response, high force measurement range, reliability and low cost make the proposed tactile sensor suitable for the force feedback in the robotic surgical systems.

Taking inspiration from human tactile system, a sensitive biomimetic multimodal tactile sensor for discrimination of static and dynamic forces is presented in this paper. The multimodal tactile sensor has a piezoelectric-capacitive tandem for responding to the dynamic and static forces respectively. Sensor can cater to normal direction dynamic force signals with a piezoelectric part operating in the d33 mode and static force with a capacitive part. The capacitive sensing part has a unique configuration with a top electrode and two sets of differential pairs electrodes for the force measurement in x and y shear axis, and one electrode for normal force measurement. The experimental characterization of the sensor was performed for static, quasi-static and dynamic forces. Along with the static forces the sensor was also able to cater to dynamic forces up to 60 Hz. The force sensitivity of the sensor for the normal force is 0.084 pF/N and 0.035 V/N from the capacitive and piezoelectric part respectively for a force range of 10 N. Also, in the shear X and Y direction the sensor exhibited a sensitivity of 0.027 pF/N and 0.029 pF/N respectively in the force range of 1.2 N. Through the vibrotactile data, the sensor showed an ability to discriminate between two texture samples through a neural network classifier. The presented sensor owing to its dimension, performance and capabilities can find its application in minimally invasive robotic surgery, robotics, wearable devices, and prosthetics.

Purpose: This paper aims to introduce a sensorized surgical grasper with a novel flexible capacitive tactile force sensor integrated within the surgical grasper for minimally invasive surgery (MIS) and robot-assisted MIS (RMIS) procedures. Design/methodology/approach: The proposed sensor offers a unique configuration of sensing electrodes with one top excitation electrode and three bottom electrodes enabling the measurement of normal and shear forces without incorporating any complex decoupling algorithms. The design of the sensor is optimized using finite-element method simulations, ensuring efficiency and reliability. Findings: Experimental validation, real-time sensor response and application in lump detection through stiffness assessment demonstrate the decoupled force response (0–5 N normal range and 0–2 N shear range) with high sensitivity 0.0124/N, repeatability and hysteresis response with 5.65% and 4.7% errors respectively. Originality/value: The compact design of the sensor makes it compliant with surgical graspers and therefore enhances the overall efficiency of robotic surgical procedures. The sensorized surgical grasper is fabricated using conventional machining and rapid prototyping techniques, presenting a cost-effective solution for adoption.

In this work we report the integration of a thin SmCo-based permanent magnetic stack within a released silicon Micro-electro-mechanical systems (MEMSs) structure, using a fabrication process compatible with standard micromachining and release techniques. A W/SmCo/W multilayer (1 μ m total thickness) is embedded into a suspended magnetic-torque magnetometer through a trench-assisted lift-off process, followed by post-deposition annealing to promote magnetic crystallization. Magnetic characterization of patterned films shows a reduction in coercivity and remanent magnetization compared to continuous layers, attributed to edge and process-induced effects. Despite these limitations, the fabricated devices exhibit measurable magnetic actuation under weak external fields. In particular, a displacement sensitivity of approximately 15 nm mT − 1 is experimentally observed under an AC magnetic field, in reasonable agreement with theoretical estimates. The proposed approach demonstrates the feasibility of integrating high-coercivity permanent magnetic materials into released MEMS geometries, enabling compact magnetic functionality for sensing and actuation applications.