cs.ROOct 7, 2026

Hall Effect-Based Tactile Force Detection Sensor for Robot-Assisted Minimally Invasive Surgery

Authors: Charles DeLorey, Michael Brockdorff, Adam Metcalf, Benjamin Calmé, Pietro Valdastri, Dominic Jones

Organizations: STORM Lab, School of Electronic and Electrical Engineering, University of Leeds, Leeds, UK

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Abstract

Robotic minimally invasive surgery has revolutionized surgical practice. However, as the surgeons are mechanically separated from the surgical tools, loss of tactile feedback occurs. We present a compact force sensor with three, millimeter scale sensing elements (taxels) that can be affixed to the grasping face of a robotic surgical tool. The sensor features a miniaturized design using Hall effect sensors and magnets embedded in a deformable elastomer contact layer. Sensor calibration is achieved with a 6 degree of freedom (DoF) parallel robot. Each taxel can detect applied normal and shear forces with average RMSE of 2.133 kPa. The calibrated sensor was validated on phantom and ex vivo porcine tissue, demonstrating tactile sensing during retraction as well as slip. This work introduces a small-scale Hall effect based tactile sensor, enabling sensing for force-sensitive robotic surgical applications.

Figures & tables

Fig. 1 : Force sensor in (a) freeform tissue grasping, (b) the assembled sensor on instrument and (c) analogous bioinspired fingertip pinch inspiration.
SensorDoFPrincipleTaxel numberSizeRange/Resolution
This work3Magnetic (Hall)32.50 ×\times 1.20 mm0–255 kPa; RMSE 2.13 kPa ( σ\sigma =1.97)
[ 6 ]3Piezoresistive14.5 ×\times 2.7 mm1.2 N normal, 0.6 N shear; 0.228 mN (Z) resolution
[ 20 ]2Capacitive16 ×\times 4 mm0–5 N normal, 0–2 N shear; 0.0124 N resolution
[ 11 ]3Optical waveguide12.6 ×\times 2.6 mm0–3 N normal, shear; 0.089 N resolution
[ 4 ]3Magnetic (Hall)1∼\sim 15 ×\times 15 mm7.12 N normal; error 9.52%
[ 3 ]3Load cell19.5 ×\times 8.5 mm±\pm 5 N axial, ±\pm 3 N lateral; error << 0.15 N ( << 11%)
TABLE I : Comparison of jaw-mounted force sensors for surgical robot instruments.
Fig. 2 : Sensing principle of Hall effect based sensors. a) Steady state measurement, b) Increase in contact pressure only displaces magnet vertically, giving a stronger field response ( BzB_{z} ); and c) A combined pressure and shear load displaces diagonally, changing the field response in both ByB_{y} and BzB_{z} .
Fig. 3 : Design and manufacture of the tactile sensor array: Manufacturing process of the skin (a) place taxel magnets into mold, then (b) cast Ecoflex 00-30 elastomer overtop small magnets and cure, (c) remove cured elastomer with encased small magnets, leaving the (d) final profile.
Fig. 4 : a) Schematic section view: (i) Original grasper jaw, (ii) elastomer layer, (iii) taxel magnet, (iv) PCB, (v) 3D-printed mount; b) Sensor mounted in fenestrated forceps.
Fig. 5 : Force sensor PCB render with individual sensors and taxel pairs, and the sensor magnetic axes.
 Pressure Error (RMSE), kPa
 Taxel 1Taxel 2Taxel 3
fx RMSE kPa1.460.670.74
fy RMSE kPa0.720.770.78
fz RMSE kPa4.85.43.9
TABLE II : Calibration results by taxel.
Taxel 1 Taxel 2 Taxel 3
 Taxel 1Taxel 2Taxel 3
Hysteresis (%, [std])14.75 [0.68]10.67 [0.39]13.55 [1.17]
Creep (% drop)4.491.713.81
Creep (correlation)0.9960.9970.995
TABLE III : Characterization results.
 Pressure Mean (Std), kPa
 Taxel 1Taxel 2Taxel 3
fx kPa0.517 (0.179)1.137 (0.122)-3.905 (0.279)
fy kPa-2.634 (0.329)-1.296 (0.503)5.611 (0.318)
fz kPa-12.281 (0.650)-6.427 (0.879)-15.020 (2.745)
TABLE IV : Mean and standard deviation during angular displacement [-40°, +40°].
 Taxel 1Taxel 2Taxel 3
Taxel 1-8.19.9
Taxel 25.6-5.7
Taxel 32.23.9-
TABLE V : Crosstalk (%) between taxels, Z-axis.
Fig. 7 : Calibration setup, top view.
Fig. 8 : Calibration procedure at sensor surface (Not to Scale). The blue indenter is pressed into the surface to a depth ( dd ) at an angle from the normal ( θ\theta ). Each value of theta is indented eight times around normal axis ( zz ), forming several concentric cones. a) and b) show the cross sectional and planar endpoints.
Fig. 9 : Experimental setup with da Vinci fenestrated bipolar forceps instrument.
Fig. 10 : Retraction and slip experiments on silicone tissue simulant.
Fig. 11 : Retraction and slip experiments on porcine tissue.
Fig. 12 : Freeform tissue grasping experiment, showing tissue slip during manipulation and repeated tissue palpation.

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