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A miniaturized sensor for needle tip force measurements

Hatzfeld, Christian and Wismath, Sonja and Hessinger, Markus and Werthschützky, Roland and Schlaefer, Alexander and Kupnik, Mario (2017):
A miniaturized sensor for needle tip force measurements.
62, pp. s109, ISSN 00135585, [Online-Edition: https://www.degruyter.com/view/j/bmte.2017.62.issue-s1/bmt-2...],
[Conference or Workshop Item]

Abstract

Needle insertion is a common medical task. Certain procedures such as brachytherapy, biopsies or punctures of peri-cardial effusions require the insertion of comparably thick needles (Ø 1 mm) into human tissue. A large risk of addi-tional tissue damaging exists because of the needle size. Additionally, the needle compresses and displaces tissue adja-cent to the cutting site, which hinders the comparison with pre-operative imaging and, therefore, exact needle place-ment. Approaches such as haptic feedback in training scenarios or as an assistive mean during an intervention are investigat-ed in order to minimize tissue damage and unwanted puncture of valuable structures. Integration of additional sensors (such as optical coherence tomography equipment integrated in the needle tip) is researched to improve position accu-racy. A pre-requirement for these techniques are accurate force measurements of the interaction forces at the needle tip. In this work we present a force sensor that can be integrated in a needle tip with a diameter of 1.2 mm and a minimum length of 7 mm. It is manufactured by the conjunction of two half-shells, which are equipped with a specially designed semi-conductor strain gauge (gain factor k ≈ 40). The application of the strain gauges to the unconnected half-shells is alleviated because of the good accessibility of the planar application surface. The strain gauge compromises a full-bridge-circuit in an area of 0.5 × 0.5 mm² and thus an decreased sensitivity to temperature influences. Electrical con-nection is made by a flexible PCB that is connected to the strain gauge before mechanical bonding with cyanacrylate adhesive. The PCB is integrated in the needle for connection to DAQ equipment. The force sensor has a nominal range of 10 N and exhibits a sensitivity of 3.2 mV/V/N, thus, lowering the requirements on the sensor electronics. Torque measurement is possible by usage of a different strain gauge design.

Item Type: Conference or Workshop Item
Erschienen: 2017
Creators: Hatzfeld, Christian and Wismath, Sonja and Hessinger, Markus and Werthschützky, Roland and Schlaefer, Alexander and Kupnik, Mario
Title: A miniaturized sensor for needle tip force measurements
Language: English
Abstract:

Needle insertion is a common medical task. Certain procedures such as brachytherapy, biopsies or punctures of peri-cardial effusions require the insertion of comparably thick needles (Ø 1 mm) into human tissue. A large risk of addi-tional tissue damaging exists because of the needle size. Additionally, the needle compresses and displaces tissue adja-cent to the cutting site, which hinders the comparison with pre-operative imaging and, therefore, exact needle place-ment. Approaches such as haptic feedback in training scenarios or as an assistive mean during an intervention are investigat-ed in order to minimize tissue damage and unwanted puncture of valuable structures. Integration of additional sensors (such as optical coherence tomography equipment integrated in the needle tip) is researched to improve position accu-racy. A pre-requirement for these techniques are accurate force measurements of the interaction forces at the needle tip. In this work we present a force sensor that can be integrated in a needle tip with a diameter of 1.2 mm and a minimum length of 7 mm. It is manufactured by the conjunction of two half-shells, which are equipped with a specially designed semi-conductor strain gauge (gain factor k ≈ 40). The application of the strain gauges to the unconnected half-shells is alleviated because of the good accessibility of the planar application surface. The strain gauge compromises a full-bridge-circuit in an area of 0.5 × 0.5 mm² and thus an decreased sensitivity to temperature influences. Electrical con-nection is made by a flexible PCB that is connected to the strain gauge before mechanical bonding with cyanacrylate adhesive. The PCB is integrated in the needle for connection to DAQ equipment. The force sensor has a nominal range of 10 N and exhibits a sensitivity of 3.2 mV/V/N, thus, lowering the requirements on the sensor electronics. Torque measurement is possible by usage of a different strain gauge design.

Journal or Publication Title: Biomedical Engineering / Biomedizinische Technik
Volume: 62
Divisions: 18 Department of Electrical Engineering and Information Technology > Institute for Electromechanical Design
18 Department of Electrical Engineering and Information Technology > Institute for Electromechanical Design > Measurement and Sensor Technology
18 Department of Electrical Engineering and Information Technology
Date Deposited: 09 Oct 2017 12:53
Official URL: https://www.degruyter.com/view/j/bmte.2017.62.issue-s1/bmt-2...
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