Design and qualitative evaluation of tactile devices for stroke rehabilitation

Abstract

Rehabilitation environments combining virtual reality with everyday motor tasks can promote recovery from neurological illness, such as stroke. Tactile devices, providing physical stimulation to the skin, may improve motor retraining. While many tactile devices have been reported, there is a distinct paucity of studies evaluating how they are perceived. This multidisciplinary research has investigated three tactile devices (vibration motors, a motor-driven 'squeezer', and shape memory alloys) for providing a realistic sensation of static interaction with virtual objects. These devices have been iteratively redesigned and qualitatively evaluated with healthy human participants. This paper presents the devices, their evaluation, and iterative redesign.

A narrative review on haptic devices: relating the physiology and psychophysical properties of the hand to devices for rehabilitation in central nervous system disorders

“…Finger movements are translated into actions on the screen and feedback is provided to the fingers through the mechanical levers [49]. These forces activate the kinaesthetic afferents in the ligaments and capsule, the muscle spindles and golgi tendon organs.…”

“…As a result, tactile displays have been described as being capable of closely replicating the tactile parameters of an object including temperature, texture, shape and roughness [63]. Used alongside computerdisplayed virtual reality environments, tactile haptic systems can provide experience of completing everyday interactions with the environment [49].…”

“…Individuals, who are unable to perceive a 10g force, when applied to the skin, should be investigated for potential underlying neuropathological damage Tactile haptic devices have been developed that capitalise on pressure sense. These include:  Devices that use a motor to constrict a band worn around the fingertip [49] [79];  Devices utilising electrorheological or magnetorheological fluids that change their viscosity [80];…”

“… Ultrasound, which may also target the FA-II afferents generating light touch [81]; and  Shape memory alloys that change shape when an electric current is passed through the alloy thus constricting the finger and generating pressure [49] [82] [83].…”

“…Recent research [49] has however, tested the feasibility of using these devices by exploring the sensations healthy people (n=7) and people with stroke (n=4) perceived when wearing i) motor constrictor and ii) shape memory alloy devices This study illustrated that pressure applied simultaneously to the volar pads of the thumb and index fingers generated a perception of holding something, indicating the potential for these devices to be used to simulate objects in VR environments. This sensation was, however, only reported by one of the people with stroke; a man who had only minor loss of light and deep touch.…”