Cell phone based balance trainer

Background: in their current laboratory-based form,existing vibrotactile sensory augmentation technologies that provide cues of body motion are impractical for home-based rehabilitation use due to their size,weight,complexity,calibration procedures,cost,and fragility. methods. we have designed and developed a cell phone based vibrotactile feedback system for potential use in balance rehabilitation training in clinical and home environments. it comprises an iphone with an embedded tri-axial linear accelerometer,custom software to estimate body tilt,a tactor bud accessory that plugs into the headphone jack to provide vibrotactile cues of body tilt,and a battery. five young healthy subjects (24 2.8 yrs,3 females and 2 males) and four subjects with vestibular deficits (42.25 13.5 yrs,2 females and 2 males) participated in a proof-of-concept study to evaluate the effectiveness of the system. healthy subjects used the system with eyes closed during romberg,semi-tandem romberg,and tandem romberg stances. subjects with vestibular deficits used the system with both eyes-open and eyes-closed conditions during semi-tandem romberg stance. vibrotactile feedback was provided when the subject exceeded either an anterior-posterior (a/p) or a medial-lateral (m/l) body tilt threshold. subjects were instructed to move away from the vibration. results: the system was capable of providing real-time vibrotactile cues that informed corrective postural responses. when feedback was available,both healthy subjects and those with vestibular deficits significantly reduced their a/p or m/l rms sway (depending on the direction of feedback),had significantly smaller elliptical area fits to their sway trajectory,spent a significantly greater mean percentage time within the no feedback zone,and showed a significantly greater a/p or m/l mean power frequency. conclusion: the results suggest that the real-time feedback provided by this system can be used to reduce body sway. its advantages over more complex laboratory-based and commercial balance training systems in terms of cost,size,weight,functionality,flexibility,and accessibility make it a good candidate for further home-based balance training evaluation. © 2012 lee et al; licensee biomed central ltd.