A Wireless Embedded Tongue Tactile Biofeedback System for Balance Control

We describe the architecture of an original biofeedback system for balance improvement for fall prevention and present results of a feasibility study. The underlying principle of this biofeedback consists of providing supplementary information related to foot sole pressure distribution through a wireless embedded tongue-placed tactile output device. Twelve young healthy adults voluntarily participated in this experiment. They were asked to stand as immobile as possible with their eyes closed in two conditions of nobiofeedback and biofeedback. Centre of foot pressure (CoP) displacements were recorded using a force platform. Results showed reduced CoP displacements in the biofeedback relative to the no-biofeedback condition. On the whole, the present findings evidence the effectiveness of this system in improving postural control on young healthy adults. Further investigations are needed to strengthen the potential clinical value of this device.Comment: Pervasive and Mobile Computing (2008) in pres

Artificial Tongue-Placed Tactile Biofeedback for perceptual supplementation: application to human disability and biomedical engineering

The present paper aims at introducing the innovative technologies, based on the concept of "sensory substitution" or "perceptual supplementation", we are developing in the fields of human disability and biomedical engineering. Precisely, our goal is to design, develop and validate practical assistive biomedical and/technical devices and/or rehabilitating procedures for persons with disabilities, using artificial tongue-placed tactile biofeedback systems. Proposed applications are dealing with: (1) pressure sores prevention in case of spinal cord injuries (persons with paraplegia, or tetraplegia); (2) ankle proprioceptive acuity improvement for driving assistance in older and/or disabled adults; and (3) balance control improvement to prevent fall in older and/or disabled adults. This paper presents results of three feasibility studies performed on young healthy adults

Can a Plantar Pressure-Based Tongue-Placed Electrotactile Biofeedback Improve Postural Control Under Altered Vestibular and Neck Proprioceptive Conditions?

We investigated the effects of a plantar pressure-based tongue-placed electrotactile biofeedback on postural control during quiet standing under normal and altered vestibular and neck proprioceptive conditions. To achieve this goal, fourteen young healthy adults were asked to stand upright as immobile as possible with their eyes closed in two Neutral and Extended head postures and two conditions of No-biofeedback and Biofeedback. The underlying principle of the biofeedback consisted of providing supplementary information related to foot sole pressure distribution through a wireless embedded tongue-placed tactile output device. Centre of foot pressure (CoP) displacements were recorded using a plantar pressure data acquisition system. Results showed that (1) the Extended head posture yielded increased CoP displacements relative to the Neutral head posture in the No-biofeedback condition, with a greater effect along the anteroposterior than mediolateral axis, whereas (2) no significant difference between the two Neutral and Extended head postures was observed in the Biofeedback condition. The present findings suggested that the availability of the plantar pressure-based tongue-placed electrotactile biofeedback allowed the subjects to suppress the destabilizing effect induced by the disruption of vestibular and neck proprioceptive inputs associated with the head extended posture. These results are discussed according to the sensory re-weighting hypothesis, whereby the central nervous system would dynamically and selectively adjust the relative contributions of sensory inputs (i.e., the sensory weights) to maintain upright stance depending on the sensory contexts and the neuromuscular constraints acting on the subject

A Wireless Lingual Feedback Device to Reduce Overpressures in Seated Posture: A Feasibility Study

BACKGROUND:Pressure sores are localized injuries to the skin and underlying tissues and are mainly resulting from overpressure. Paraplegic peoples are particularly subjects to pressure sores because of long-time seated postures and sensory deprivation at the lower limbs. METHODOLOGY/PRINCIPAL FINDINGS:Here we report outcomes of a feasibility trial involving a biofeedback system aimed at reducing buttock overpressure whilst an individual is seated. The system consists of (1) pressure sensors, (2) a laptop coupling sensors and actuator (3) a wireless Tongue Display Unit (TDU) consisting of a circuit embedded in a dental retainer with electrodes put in contact with the tongue. The principle consists in (1) detecting overpressures in people who are seated over long periods of time, (2) estimating a postural change that could reduce these overpressures and (3) communicating this change through directional information transmitted by the TDU.Twenty-four healthy subjects voluntarily participated in this study. Twelve healthy subjects initially formed the experimental group (EG) and were seated on a chair with the wireless TDU inside their mouth. They were asked to follow TDU orders that were randomly spread throughout the session. They were evaluated during two experimental sessions during which 20 electro-stimulations were sent. Twelve other subjects, added retrospectively, formed the control group (CG). These subjects participated in one session of the same experiment without any biofeedback.Three dependent variables were computed: (1) the ability of subjects to reach target posture (EG versus CG), (2) high pressure reductions after a biofeedback (EG versus CG) and (3) the level of these reductions relative to their initial values (EG only). Results show (1) that EG reached target postures in 90.2% of the trials, against 5,3% in the CG, (2) a significant reduction in overpressures in the EG compared to the CG and (3), for the EG, that the higher the initial pressures were, the more they were decreased. CONCLUSIONS/SIGNIFICANCE:The findings suggest that, in this trial, subjects were able to use a tongue tactile feedback system to reduce buttock overpressure while seated. Further evaluation of this system on paraplegic subjects remains to be done

Haptic wearables as sensory replacement, sensory augmentation and trainer - a review

Sensory impairments decrease quality of life and can slow or hinder rehabilitation. Small, computationally powerful electronics have enabled the recent development of wearable systems aimed to improve function for individuals with sensory impairments. The purpose of this review is to synthesize current haptic wearable research for clinical applications involving sensory impairments. We define haptic wearables as untethered, ungrounded body worn devices that interact with skin directly or through clothing and can be used in natural environments outside a laboratory. Results of this review are categorized by degree of sensory impairment. Total impairment, such as in an amputee, blind, or deaf individual, involves haptics acting as sensory replacement; partial impairment, as is common in rehabilitation, involves haptics as sensory augmentation; and no impairment involves haptics as trainer. This review found that wearable haptic devices improved function for a variety of clinical applications including: rehabilitation, prosthetics, vestibular loss, osteoarthritis, vision loss and hearing loss. Future haptic wearables development should focus on clinical needs, intuitive and multimodal haptic displays, low energy demands, and biomechanical compliance for long-term usage

Tongue Liminary Threshold Identification to Electrotactile Stimulation

Many applications use electrostimulation of the human skin to provide tactile sensation. The effect of electrotactile stimulations were studied on a 6x6 matrix of tactile electrodes placed on the anterior part of the tongue. The liminary threshold with continuous or discontinuous waveform and patterns with 2 or 4 electrodes was investigated. The result suggest that for energy saving and to improve the yield, it would probably be better to use discontinuous stimulation with two electrode patterns

iBalance-ABF: a Smartphone-Based Audio-Biofeedback Balance System

International audienceThis article proposes an implementation of a Kalman Filter, using inertial sensors of a Smartphone, to estimate 3D angulation of the trunk. The developped system monitors the trunk angular evolution during bipedal stance and helps the user to improve balance through a configurable and integrated auditory-biofeedback loop. A proof-of-concept study was performed to assess the effectiveness of this so-called iBalance-ABF - smartphone-based audio-biofeedback system - in improving balance during bipedal standing. Results showed that young healthy individuals were able to efficiently use ABF on sagittal trunk tilt to improve their balance in the ML direction. These findings suggest that iBalance-ABF system as a Telerehabilitation system which could represent a suitable solution for Ambient Assisted Living technologies

Design and Assessment of Vibrotactile Biofeedback and Instructional Systems for Balance Rehabilitation Applications.

Sensory augmentation, a type of biofeedback, is a technique for supplementing or reinforcing native sensory inputs. In the context of balance-related applications, it provides users with additional information about body motion, usually with respect to the gravito-inertial environment. Multiple studies have demonstrated that biofeedback, regardless of the feedback modality (i.e., vibrotactile, electrotactile, auditory), decreases body sway during real-time use within a laboratory setting. However, in their current laboratory-based form, existing vibrotactile biofeedback devices are not appropriate for use in clinical and/or home-based rehabilitation settings due to the expense, size, and operating complexity of the instrumentation required. This dissertation describes the design, development, and preliminary assessment of two technologies that support clinical and home-based balance rehabilitation training. The first system provides vibrotactile-based instructional motion cues to a trainee based on the measured difference between the expert’s and trainee’s motions. The design of the vibrotactile display is supported by a study that characterizes the non-volitional postural responses to vibrotactile stimulation applied to the torso. This study shows that vibration applied individually by tactors over the internal oblique and erector spinae muscles induces a postural shift of the order of one degree oriented in the direction of the stimulation. Furthermore, human performance is characterized both experimentally and theoretically when the expert–trainee error thresholds and nature of the control signal are varied. The results suggest that expert–subject cross-correlation values were maximized and position errors and time delays were minimized when the controller uses a 0.5 error threshold and proportional plus derivative feedback control signal, and that subject performance decreases as motion speed and complexity increase. The second system provides vibrotactile biofeedback about body motion using a cell phone. The system is capable of providing real-time vibrotactile cues that inform corrective trunk tilt responses. When feedback is available, both healthy subjects and those with vestibular involvement significantly reduce their anterior-posterior or medial-lateral root-mean-square body sway, have significantly smaller elliptical area fits to their sway trajectory, spend a significantly greater mean percentage time within the no feedback zone, and show a significantly greater A/P or M/L mean power frequency.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91546/1/channy_1.pd

Pressure Sores Prevention for Paraplegic People: Effects of Visual, Auditory and Tactile Supplementations on Overpressures Distribution in Seated Posture

This paper presents a study on the usage of different informative modalities as biofeedbacks of a perceptual supplementation device aiming at reducing overpressure at the buttock area. Visual, audio and lingual electrotactile modalities are analysed and compared with a non-biofeedback session. In conclusion, sensory modalities have a positive and equal effect, but they are not equally judged in terms of comfort and disturbance with some other activities