Encoder-controlled functional electrical stimulator for stroke rehabilitation: a usability study

Numerous therapeutic interventions have been explored for stroke related dysfunctions with various degrees of success; however, rehabilitation of the stroke-affected upper limb and hand still remains a challenge. Focus has now shifted to rehabilitative training devices that augment neuroplasticity and improve motor control. This article discusses a usability study carried out on a novel device called the encoder-controlled FES. It uses flexion and extension of the unaffected wrist to control the delivery of stimulation to the stroke affected wrist, resulting in a mirrored activity of the unaffected wrist on the stroke-affected wrist. The hypothesis was that a combination of bilateral arm training and FES mediated mirrored wrist activity will help the brain to relearn the activity and improve motor control. A preliminary usability study was conducted to check the acceptability of the device being used in a clinical setting. The device was used by 20 patients with stroke and 15 occupational/physiotherapists in a single session each. After the session, patients filled in three feedback forms – the System Usability Scale (SUS), the User Experience Questionnaire (UEQ) and an EC-FES patient questionnaire; the therapists were given an EC-FES therapist questionnaire. The mean scores obtained for the SUS test and patient questionnaire were 74 ± 16.3, and 78.26 ± 8.54 respectively. All the questions in the UEQ were answered positively, conveying that the device meets participants expectations, and the mean score obtained for the therapist questionnaire was 75.3 ± 14.93. The scores suggest that the device may be useable in a clinical setting and paves the way for further definitive trials.