Many devices are available on the market for the evaluation and rehabilitation of patients suffering from muscular disorders. Most of them are small, low-cost, passive devices based on the use of springs and resistive elements and exhibit very limited (or even not any) evaluation capabilities; extended muscular force evaluation is only possible on stationary, expensive, multi-purpose devices, available only in hospitals, which offer many exercise modes (e.g. isokinetic mode) that are not available on other devices. The objective of this thesis is to make the functionalities currently only implemented on bulky multi-purpose devices available at a lower cost and in a portable fashion, enabling their use by a large number of independent practitioners and patients, even at home (tele-medecine applications). In order to achieve this goal, a portable rehabilitation device, using a magneto-rheological fluid brake as actuator, has been designed. This particular technology was selected for its high level of compactness, simple mechanical design, high controllability, smooth and safe operation. The first part of this thesis is devoted to the design of MR-fluid brakes and their experimental validation. The second part is dedicated to the design of the rehabilitation device and the comparison of its performances with a commercial multi-purpose device (CYBEX).

In order for stroke subjects to gain functional recovery of their hemiparetic limbs, facilitation techniques such as the repetitive facilitation exercise, or RFE, have been developed. Currently, there is a lack of understanding of the neural mechanisms associated with these types of facilitation techniques. To better understand the neural mechanisms associated with the RFE a functional magnetic resonance imaging (fMRI) study should be conducted. This thesis presents experimental results testing the feasibility of implementing an fMRI-compatible actuator to facilitate a myotatic reflex in synchronization with the subject’s intention to move their hemiparetic limb. Preliminary data from a healthy individual demonstrated the feasibility of overlapping the long latency component of the afferent myotatic reflex, created by electrical stimulation, with descending nerve impulses, created using transcranial magnetic stimulation, in a time window of 15ms. In addition, a pneumatic actuation time delay due to long transmission line was evaluated. The pneumatic actuator met the timing precision requirement for the rehabilitation device for varying transmission line lengths. Therefore a pneumatic actuation system was chosen for the rehabilitation device. This thesis will also presents on the design of an fMRI-compatible pneumatic actuator device to excite a stretch reflex response. Initial, experimental results with the device demonstrated that the designed pneumatic device can control the timing of the muscle response with a fixed signal within the required 15ms window required for cortical facilitation, which was found in the previous feasibility study. However, the device was unable to create a long latency reflex observable at the muscle. Finally, this thesis presents on the capability of the device in creating subthreshold long latency response with precision to overlap with a subthreshold descending nerve impulse, created using transcranial magnetic stimulation. The overlap of the two responses was evaluated by comparing the amplitude of the muscle response with and without the stretch reflex, created by the fMRI-compatible pneumatic actuator device. Varying time delays were analyzed.

Many devices are available on the market for the evaluation and rehabilitation of patients suffering from muscular disorders. Most of them are small, low-cost, passive devices based on the use of springs and resistive elements and exhibit very limited (or even not any) evaluation capabilities; extended muscular force evaluation is only possible on stationary, expensive, multi-purpose devices, available only in hospitals, which offer many exercise modes (e.g. isokinetic mode) that are not available on other devices.<p><p>The objective of this thesis is to make the functionalities currently only implemented on bulky multi-purpose devices available at a lower cost and in a portable fashion, enabling their use by a large number of independent practitioners and patients, even at home (tele-medecine applications).<p><p>In order to achieve this goal, a portable rehabilitation device, using a magneto-rheological fluid brake as actuator, has been designed. This particular technology was selected for its high level of compactness, simple mechanical design, high controllability, smooth and safe operation. The first part of this thesis is devoted to the design of MR-fluid brakes and their experimental validation. The second part is dedicated to the design of the rehabilitation device and the comparison of its performances with a commercial multi-purpose device (CYBEX). / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished