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Development of Tendon force Transducer for neuroprostheses

Objective

Functional Electrical Stimulation (FES) is used to restore functional abilities in disabled people. The idea of FES systems is to stimulate a particular motor nerve or skeletal muscle with electric current with the intention to get functionally useful muscle contraction. A proper use of FES is not possible without proper regulation of stimuli. The common obstacle that prevents wider use of these appliances is the difficulty to control muscle function during electric stimulation properly. The goal of the project is to develop a new innovative type artificial implantable tendon transducer that can measure force and tendon movement concomitantly A valid position and movement information with exact knowledge about muscle force produced given by novel force and movement transducer will make an acceptable control and regulation of movements possible. An adequate control system is a prerequisite for bringing functional electrical stimulation into everyday life in handicapped people. Functional Electrical Stimulation (FES) is used to restore functional abilities in disabled people. The idea of FES systems is to stimulate a particular motor nerve or skeletal muscle with electric current with the intention to get functionally useful muscle contraction. A proper use of FES is not possible without proper regulation of stimuli. The common obstacle that prevents wider use of these appliances is the difficulty to control muscle function during electric stimulation properly. The goal of the project is to develop a new innovative type artificial implantable tendon transducer that can measure force and tendon movement concomitantly A valid position and movement information with exact knowledge about muscle force produced given by novel force and movement transducer will make an acceptable control and regulation of movements possible. An adequate control system is a prerequisite for bringing functional electrical stimulation into everyday life in handicapped people.

OBJECTIVES
A valid joint position and movement information with exact knowledge about muscle force produced is a prerequisite for acceptable control and regulation of movements achieved with functional electrical muscle stimulation. The movements of tendons have a direct relationship with joint movements. As well, the force transmitted through a tendon has a direct relationship with the force generated by muscle contraction. The goal of this project is to develop a new type of tendon transducer that can measure force and tendon movement concomitantly. The accurate joint position and movement information in multiple joints is necessary for bringing functional electrical stimulation into everyday life in handicapped people e.g. for controlling automatic paraplegic gait, the drop-foot of stroke patients or hand and finger movement and grip forces in quadriplegic subjects. The risk of complications of the novel sensor is apparently smaller than with intra-articular or intra-tendinous transducers.

DESCRIPTION OF WORK
The purpose of the present work is to create the basis for future research and developing work. After the three first steps it can be judged whether it is possible to continue experimental work in this field and which are the most important challenges in the future:
1) The prerequisites for the definition of exact requirements for the sensory transducer area) the exact definition of the viscoelastic and fatigue properties of the tendons and b) the determination of the possible dimensions of the transducer in different tendons which depends e.g. on the thickness and the free space around different tendons. For assessing sliding of the tendons c) the demonstration of the qualifications for the possible tendon movement reference point is necessary;
2) The design and construction of the transducer In the first step, the transducer could not be completely integrated: the force, the slippage, the deformation and the shape sensors could be independent modules to be set up in a suitable arrangement for the in vitro tests. This preliminary configuration could also help to analyse the sensors behaviour and to indicate the best integration solution for the future project;
3) In vitro testing of the transducer mechanics includes a) calibration of the novel transducer force recording capabilities with different tendon specimens in different stress conditions and b) the sensitivity to measure sliding movements in vitro. If this has been successful it is possible to assess whether the construction of transducer for in vivo conditions is possible.

Funding Scheme

ACM - Preparatory, accompanying and support measures

Coordinator

INVALIDISAATIO
Address
Tenholantie 10
00280 Helsinki
Finland

Participants (1)

SCUOLA SUPERIORE DI STUDI UNIVERSITARI E DI PERFEZIONAMENTO SANT'ANNA
Italy
Address
Piazza Martiri Della Liberta, 33
56127 Pisa