InViFoSens - In Vivo Force Sensing for Human Tissue Characterisation

Duration: January 2015 to February 2017

In the research project funded by the BMBF (16SV7200K), the mechanical characteristics of human tissue are under investigation. Tissue interaction forces are mostly unknown during surgical in vivo operations. There is a great interest in obtaining the mechanical measurement data for:

1) Training simulators to teach future surgeons haptic perception

2) Real-time force feedback for a surgical robot or surgeon with  currently applied stresses, strains and maximum load limits of the tissue to ensure patient’s safety.

The main objective of this work is the development of a compact force/torque sensor unit, which is small enough to be integrated in almost every surgical instrument or device.

In the first design progress, a handheld surgical grip is manufactured that provides space for the electro-mechanical components of the sensor device. The figure on the right shows a surgical instrument attached to the grip with the integrated sensor system. The force/torque interaction with the organic tissue is transferred from the tool tip of the rigid surgical instrument and a tight fit coupling into the sensor element. The coupling enables a simple exchange of surgical instruments, e.g. scalpels, rasps or hooks. The measured force/torque signal is processed (transformation and filtering) in the sensor electronics unit and transferred to a display device via wireless transmission.

The focus of the project at the Measurement and sensor technology group is on the design progress of the sensor element, consisting of a spoke wheel deformation element with a diameter of 12 mm and eight inhomogeneous doped piezoresistive silicon strain gauges on an integrated full-bridge assembly with an edge length of 500 μm. The silicon chips are contacted to flex-circuits via flip chip and bonded on the substrate with a single component adhesive. A signal processing board with an 18 bit serial A/D converter is integrated into the sensor. The figure below shows the sensor case design and system components of the 6 DOF force/torque sensor.

Our research partner Innovative Surgical Training Technologies (ISTT) at HWTK Leipzig works on the medical tissue measurements and haptic training simulator design.

Research Group

  • Measurement and sensor technology (MuST), TU Darmstadt (Prof. R. Werthschützky, Dr. P. Pott) - Sensor design, packaging, electronics and characterisation – Markus Hessinger
  • Innovative Surgical Training Technologies (ISTT), HWTK Leipzig (Prof. Dr. sc. hum. Werner Korb) - Development of electronics and software - Tobias Pilic

Publications

  • Hessinger, M.; Pilic, T.; Werthschützky, R.; Pott, P. P. : Multiaxial Force Sensor for Tissue Characteristics Measurements. In: Dreiländertagung - Swiss, Austrian and German Societies of Biomedical Engineering (BMT 2016), Basel, Swiss 2016.
  • Hessinger, M.; Hielscher, J., Pott, P. P.; Werthschützky, R. : Miniaturized Piezoresistive Sensor for Multiaxial In-Situ Force Measurements. In: XXX. Messtechnisches Symposium des Arbeitskreises der Hochschullehrer für Messtechnik, Hannover, Deutschland 2016.
  • Hessinger, M.; Pilic, T.; Werthschützky R., Pott, P. P. : Miniaturized Force/Torque Sensor for In Vivo Measurements of Tissue Characteristics. In: 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Orlando, Florida, USA 2016.

Contact

Markus Hessinger

Dr. Peter P. Pott

Kontakt

Technische Universität Darmstadt

Institut für Elektromechanische Konstruktionen

Mikrotechnik

Prof. Dr.-Ing. Helmut F. Schlaak

S3/06 128
Merckstraße 25
64283 Darmstadt

+49 6151 16-23851
+49 6151 16-23852

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