**Conflict of interest**

*Assistive and Rehabilitation Engineering*

enhanced self-regulation and the self-use of technology.

SynPhNe system, and the effect on outcomes and independence.

Once the antagonist activity was subdued and reinforced over 2–4 sessions, the range of motion and speed was progressively increased in subsequent sessions. This was effective particularly in wrist and finger extension, which is known to be a significant challenge for most stroke patients. Control deficiencies in approach, sequential steps and object release were similarly improved with slower execution speeds that were meant to effect better proximal stabilization and reduced compensation as often seen in shoulder elevation and abduction while reaching, pronating, and grasping with the affected arm. Since the most significant improvements in percentage terms were seen in the ARAT scale which evaluates functional and participation tasks, the authors propose that the SynPhNe system impacts independence positively, combined with

All subjects tolerated the multi-modal feedback well and did not report feeling overwhelmed by the user interface and demands of the feedforward-feedback loop. It was noticed that the distribution of the visual sampling of the feedforward and feedback during the sessions differed between subjects and within subjects as therapy sessions progressed. This could be an interesting area of investigation in future studies to better understand how adults learn in a non-instructional and sensory manner. This paradigm needs to be tested further with a larger study and a 30–60 day follow-up to evaluate retention of brain-muscle strategies learnt and further generalizations to other functional activities. Two larger, case-controlled studies are underway presently with sub-acute and chronic phase patients to understand how the transition from hospital to home-based therapy may be executed using the

Training to relax specific muscles adequately and in a timely manner during therapy using a feedforward-feedback loop, instead of practicing repetitive muscle contraction alone, may help re-learn movement and daily functional activities in stroke subjects who have "plateaued" and not responding to further therapy. Simultaneous activation-relaxation training of agonist-antagonist not only facilitated improvement of functional abilities but was also well tolerated by all subjects and did not cause them to get overwhelmed by the number of feedforward and feedback elements on the computer screen. This indicated that despite the challenges brought on by stroke, patients with impairments can still leverage their sensory learning abilities in an exploratory and then goal-directed manner while attempting to regain spatial and temporal aspects of movement and function of the upper limb. Thus, they appeared to be able to re-boot how they learnt in a sensory manner as babies using the feedforward-feedback modality. A wearable device such as the SynPhNe system may, therefore, help leverage neuroplasticity and act as a key complement to conventional therapy. Being patient-led and requiring reduced therapist supervision, it can effectively augment therapy hours at home or in the community, thus holding the promise of making daily therapy accessible and

The research was funded by the National Research Foundation POC Grant and Singapore-MIT Alliance for Research and Technology (SMART) Innovation Grant, both in Singapore. Our thanks also go out to the subjects who participated and the clinical teams at Tan Tock Seng Hospital and National University Hospital, Singapore.

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**5. Conclusion**

affordable to all.

**Acknowledgements**

Subhasis Banerji and John Heng are founders and inventors of the SynPhNe system. While providing technical support and supervision to the studies, they were blinded to pre- and post-clinical assessment of subjects.

Daphne Menezes and Ponvignesh Ponnusamy are current employees of Synphne Pte. Ltd., Singapore. Daphne Menezes assisted the clinical study team as a trainer in the SynPhNe system and observer of therapy sessions. Ponvignesh Ponnusamy assisted with software programming and user interface development only. Both were blinded to pre- and post-clinical assessment of subjects.

The other authors have no conflict of interest.
