A Portable Sensory Augmentation Device for Balance Rehabilitation Using Fingertip Skin Stretch Feedback

Abstract

Neurological disorders are the leading causes of poor balance. Previous studies have shown that biofeedback can compensate for weak or missing sensory information in people with sensory deficits. These biofeedback inputs can be easily recognized and converted into proper information by the central nervous system (CNS), which integrates the appropriate sensorimotor information and stabilizes the human posture. In this study, we proposed a form of cutaneous feedback which stretches the fingertip pad with a rotational contactor, so-called skin stretch. Skin stretch at a fingertip pad can be simply perceived and its small contact area makes it favored for small wearable devices. Taking advantage of skin stretch feedback, we developed a portable sensory augmentation device (SAD) for rehabilitation of balance. SAD was designed to provide postural sway information through additional skin stretch feedback. To demonstrate the feasibility of the SAD, quiet standing on a force plate was evaluated while sensory deficits were simulated. Fifteen healthy young adults were asked to stand quietly under six sensory conditions: three levels of sensory deficits (normal, visual deficit, and visual + vestibular deficits) combined with and without augmented sensation provided by SAD. The results showed that augmented sensation via skin stretch feedback helped subjects correct their posture and balance, especially as the deficit level of sensory feedback increased. These findings demonstrate the potential use of skin stretch feedback in balance rehabilitation.

Synergistic Effects on the Elderly People's Motor Control by Wearable Skin-Stretch Device Combined with Haptic Joystick

“…This can be interpreted as follows: FC had more distinct effects on the improvement of the subjects' performance compared to the other augmented sensory feedback conditions, i.e., NA, F, and C. Even though each of F and C may not effectively enhance the safety-related metrics, the combined sensory feedback FC synergistically enhanced the safety-related metrics. This result is consistent with the findings from Shull and Damian (2015); Pan and Hur (2016); Pan et al (2017) that skin is a good receptor; therefore, cutaneous stimulations have the great feasibilities to serve as an efficient augmented sensory feedback. Similarly, for gait and balance rehabilitation trainings, the feasibility to improve learning efficiency was attested by stimulating multiple skin locations so that the subjects can perceive different haptic stimuli more accurately (Jirattigalachote et al, 2011; Lurie et al, 2011).…”

“…A haptic lever is one of the most commonly-used interfaces providing a force feedback to attract the user toward the safer or the desired directions while driving a power-wheelchair (Crespo and Reinkensmeyer, 2008; Marchal-Crespo et al, 2010a; Yoon et al, 2017) or assisting target-pointing/hitting tasks (Powell and O'Malley, 2012; Fisher et al, 2015; Patton and Huang, 2016). Vibrators or skin-stretchers have also been used to provide tactile stimulations for postural sway improvement (Gopalai and Senanayake, 2011; Pan and Hur, 2016; Pan et al, 2017), trunk sway improvement (Davis et al, 2010; Lee et al, 2012), target acquisition and pointing (Bark et al, 2010; Hsieh et al, 2014; Kaul and Rohs, 2016), balance training (Spelmezan et al, 2009; Nanhoe-Mahabier et al, 2012), gait function learning (Shull et al, 2011; Sienko et al, 2013). Several devices have been developed to provide realistic three dimensional tactile sensation to the user, e.g., touching a flat surface, grasping a virtual object, and tipping a surface or an object (Chinello et al, 2012; Prattichizzo et al, 2013; Pacchierotti et al, 2015).…”

Free Energy Principle in Human Postural Control System: Skin Stretch Feedback Reduces the Entropy

“…Specifically, upright standing involves the integration and transformation of various sensory inputs (e.g., vision, vestibular system, proprioception, touch) via a highly-coordinated central nervous system (CNS) into bodily information (e.g., position, velocity, and acceleration of body sway). Degradation in the sensory systems (e.g., vision 7, 9 proprioception 10-12 , vestibular system 8,13 , touch 3,14 ), muscular systems 15,16 and nervous systems 17,18 worsens balance of the upright standing.…”

“…One widely-accepted idea is that human sensorimotor systems utilize the error feedbacks for motor adaptation 29 . Several studies have reported that amplifying the movement errors could enhance the rehabilitation outcomes, which is sometimes referred to as an error augmentation 13,30,31 . Although rehabilitation may include internal sources of adaptation such as motor imagery, these are not the focus of this study.…”

“…Cutaneous feedback has been of a great interest as a way to sensory augmentation for the balance enhancement 13,[32][33][34] . Random vibrotactile feedback has been used to strengthen the weak signal, known as stochastic resonance, and thus improve the sensorimotor functions [35][36][37][38] .…”