Skin-Inspired Magnetoresistive Tactile Sensor for Force Characterization in Distributed Areas
Touch is a crucial sense for advanced organisms, particularly humans, as it provides essential information about the shape, size, and texture of contacting objects. In robotics and automation, the integration of tactile sensors has become increasingly relevant, enabling devices to properly interact...
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MDPI AG
2025-06-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/25/12/3724 |
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| author | Francisco Mêda Fabian Näf Tiago P. Fernandes Alexandre Bernardino Lorenzo Jamone Gonçalo Tavares Susana Cardoso |
| author_facet | Francisco Mêda Fabian Näf Tiago P. Fernandes Alexandre Bernardino Lorenzo Jamone Gonçalo Tavares Susana Cardoso |
| author_sort | Francisco Mêda |
| collection | DOAJ |
| description | Touch is a crucial sense for advanced organisms, particularly humans, as it provides essential information about the shape, size, and texture of contacting objects. In robotics and automation, the integration of tactile sensors has become increasingly relevant, enabling devices to properly interact with their environment. This study aimed to develop a biomimetic, skin-inspired tactile sensor device capable of sensing applied force, characterizing it in three dimensions, and determining the point of application. The device was designed as a 4 × 4 matrix of tunneling magnetoresistive sensors, which provide a higher sensitivity in comparison to the ones based on the Hall effect, the current standard in tactile sensors. These detect magnetic field changes along a single axis, wire-bonded to a PCB and encapsulated in epoxy. This sensing array detects the magnetic field from an overlayed magnetorheological elastomer composed of Ecoflex and 5 µm neodymium–iron–boron ferromagnetic particles. Structural integrity tests showed that the device could withstand forces above 100 N, with an epoxy coverage of 0.12 mL per sensor chip. A 3D movement stage equipped with an indenting tip and force sensor was used to collect device data, which was then used to train neural network models to predict the contact location and 3D magnitude of the applied force. The magnitude-sensing model was trained on 31,260 data points, being able to accurately characterize force with a mean absolute error ranging between 0.07 and 0.17 N. The spatial sensitivity model was trained on 171,008 points and achieved a mean absolute error of 0.26 mm when predicting the location of applied force within a sensitive area of 25.5 mm × 25.5 mm using sensors spaced 4.5 mm apart. For points outside the testing range, the mean absolute error was 0.63 mm. |
| format | Article |
| id | doaj-art-65c95091c5234232be19e59ddd5f988b |
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| issn | 1424-8220 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj-art-65c95091c5234232be19e59ddd5f988b2025-08-20T02:21:50ZengMDPI AGSensors1424-82202025-06-012512372410.3390/s25123724Skin-Inspired Magnetoresistive Tactile Sensor for Force Characterization in Distributed AreasFrancisco Mêda0Fabian Näf1Tiago P. Fernandes2Alexandre Bernardino3Lorenzo Jamone4Gonçalo Tavares5Susana Cardoso6INESC Microsistemas e Nanotecnologias (INESC-MN), 1000-029 Lisbon, PortugalINESC Microsistemas e Nanotecnologias (INESC-MN), 1000-029 Lisbon, PortugalINESC Microsistemas e Nanotecnologias (INESC-MN), 1000-029 Lisbon, PortugalInstituto Superior Técnico (IST), Universidade de Lisboa, 1049-001 Lisbon, PortugalComputer Science Department, University College London (UCL), London WC1E 6BT, UKInstituto Superior Técnico (IST), Universidade de Lisboa, 1049-001 Lisbon, PortugalINESC Microsistemas e Nanotecnologias (INESC-MN), 1000-029 Lisbon, PortugalTouch is a crucial sense for advanced organisms, particularly humans, as it provides essential information about the shape, size, and texture of contacting objects. In robotics and automation, the integration of tactile sensors has become increasingly relevant, enabling devices to properly interact with their environment. This study aimed to develop a biomimetic, skin-inspired tactile sensor device capable of sensing applied force, characterizing it in three dimensions, and determining the point of application. The device was designed as a 4 × 4 matrix of tunneling magnetoresistive sensors, which provide a higher sensitivity in comparison to the ones based on the Hall effect, the current standard in tactile sensors. These detect magnetic field changes along a single axis, wire-bonded to a PCB and encapsulated in epoxy. This sensing array detects the magnetic field from an overlayed magnetorheological elastomer composed of Ecoflex and 5 µm neodymium–iron–boron ferromagnetic particles. Structural integrity tests showed that the device could withstand forces above 100 N, with an epoxy coverage of 0.12 mL per sensor chip. A 3D movement stage equipped with an indenting tip and force sensor was used to collect device data, which was then used to train neural network models to predict the contact location and 3D magnitude of the applied force. The magnitude-sensing model was trained on 31,260 data points, being able to accurately characterize force with a mean absolute error ranging between 0.07 and 0.17 N. The spatial sensitivity model was trained on 171,008 points and achieved a mean absolute error of 0.26 mm when predicting the location of applied force within a sensitive area of 25.5 mm × 25.5 mm using sensors spaced 4.5 mm apart. For points outside the testing range, the mean absolute error was 0.63 mm.https://www.mdpi.com/1424-8220/25/12/3724tactile sensorartificial skinmagnetoresistive sensormagnetorheological elastomerneural networkinstrumentation |
| spellingShingle | Francisco Mêda Fabian Näf Tiago P. Fernandes Alexandre Bernardino Lorenzo Jamone Gonçalo Tavares Susana Cardoso Skin-Inspired Magnetoresistive Tactile Sensor for Force Characterization in Distributed Areas Sensors tactile sensor artificial skin magnetoresistive sensor magnetorheological elastomer neural network instrumentation |
| title | Skin-Inspired Magnetoresistive Tactile Sensor for Force Characterization in Distributed Areas |
| title_full | Skin-Inspired Magnetoresistive Tactile Sensor for Force Characterization in Distributed Areas |
| title_fullStr | Skin-Inspired Magnetoresistive Tactile Sensor for Force Characterization in Distributed Areas |
| title_full_unstemmed | Skin-Inspired Magnetoresistive Tactile Sensor for Force Characterization in Distributed Areas |
| title_short | Skin-Inspired Magnetoresistive Tactile Sensor for Force Characterization in Distributed Areas |
| title_sort | skin inspired magnetoresistive tactile sensor for force characterization in distributed areas |
| topic | tactile sensor artificial skin magnetoresistive sensor magnetorheological elastomer neural network instrumentation |
| url | https://www.mdpi.com/1424-8220/25/12/3724 |
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