Myoelectric Control: an alternative to Mirror Therapy

Evidence suggests that fifty to eighty percent (50-80%) of amputees conserve sensation in their missing limb after removal due to the presence of associated nerve endings. Most importantly, a large percentage of amputees experience episodic pain in the missing limb. This physiological phenomenon called phantom limb pain (PLP) has shown resistance to pharmaceutical treatments, but can be treated through mirror therapy. However, mirror therapy only yields temporary results and does not apply to bilateral amputees. Overcoming these challenges are the objectives of the present study. Using a surface electromyographic signal classification approach, this investigation intends to simulate the control of a missing limb within an immersive virtual environment. We predict that replacing mirror therapy with a more immersive “virtual therapy” can serve as a prolonged psychological solution to phantom limb pain.

A stretchable and adhesive ionic conductor based on polyacrylic acid and deep eutectic solvents

Hydrogels are a widely used ionic conductor in on-skin electronic and iontronic devices. However, hydrogels dehydrate in the open air and freeze at low temperatures, limiting their real applications when they are attached on skin or exposed to low temperatures. Polymer-ionic liquid gels can overcome these two obstacles, but synthetic ionic liquids are expensive and toxic. In this work, we present an ionic conductor based on polyacrylic acid (PAAc) and deep eutectic solvents (DESs) that well addresses the aforementioned challenges. We polymerize acrylic acid in DESs to get the PAAc–DES gel, which exhibits excellent stretchability (> 1000%), high electrical conductivity (1.26 mS cm−1), high adhesion to the skin (~ 100 N m−1), as well as good anti-drying and anti-freezing properties. We also demonstrate that the PAAc-DES gel can be used as an on-skin electrode to record the surface electromyographic signal with high signal quality, or as a transparent stretchable electrode in iontronic devices that can work at –20 °C. We believe that the PAAc–DES gels are an ideal candidate as epidermal electrodes or transparent stretchable electrodes.