Falls in people over the age of 65 is a problem that has a significant and negative impact on a country’s economy and faller’s quality of life. Despite the positive efforts to reduce falls, this problem is still in need of a solution. Some of the efforts to improve postural stability (i.e., reduce fall risk) are physical therapy, medication, and medical devices, all showing significant improvements in people’s postural stability. However, in the case of medical devices, some (canes, wheelchairs, etc.) create a stigma of weakness on the user, causing them to often choose to take chances by not using the suggested medical device. Stochastic resonance, a relative new technology, has shown positive results towards improving the somatosensory (sensation) feedback in humans, which is one type of sensory feedback used in postural stability. Stochastic resonance can be introduced in humans through mechanically vibrating their feet, making this potential medical device one that does not create a stigma of weakness among their users (i.e., it would not be visible to the public). This dissertation covers the design, manufacturing, validation, and performance assessment of a new vibratory mat that introduces stochastic resonance to the user.

In the first study, the most-reported vibratory device in stochastic resonance studies was compared to the vibratory mat that is proposed in this dissertation. By asking various questions that addressed current design requirements, and new ones that increase the likelihood of being used by the targeted populations, both vibratory devices (i.e., the one developed here and the one most-reported in the literature) were assessed. It was found that our vibratory mat follows all designed requirements and has as much potential (and possibly more) to be successful in stochastic resonance studies.

In the second study, our vibratory mat was quantified and validated by measuring the forces and frequencies it exerted at various power levels, as well as by analyzing the quality of its vibrations. Using all configurations in the vibratory mat, the exerted forces and frequencies were recorded and fitted by quadratic regression equations. The obtained regression equations accurately quantified the forces and frequencies since their fitting coefficients were R² ≥ 0.87 and R² ≥ 0.70, respectively. In addition, it was validated through experimental data if the vibratory mat could accurately execute white, pink, and brown vibrations. It was found that our vibratory mat can exert white, pink, and brown vibrations, and that the quality of the signals increase as larger motors and power levels are used.

The final study of this dissertation consisted of quantifying the impact of subthreshold vibration (i.e., stochastic resonance) in small groups of healthy older adults and healthy younger adults who stood on a 1-inch foam to simulate a sensory deficit. This was tested by introducing white, pink, brown, and placebo vibrations across 4 different visits, and recording their center of pressure prior, during and after the vibration. The first result from this study was that the use of 1-inch foam in healthy younger participants has the potential to simulate aging in future stochastic resonance studies. The second significant result is that subthreshold vibration is dependent on the state of postural stability prior to the vibration. Indicating that it is possible that more than one type of vibration could benefit people’s postural stability, and that the most beneficial vibration to a participant could change day-to-day depending on the participant’s state of postural stability. This implies a personalized medicine approach, in which the vibration treatment is customized for the individual on the day of the treatment. Finally, our results agreed with previous stochastic resonance studies towards the evidence that subthreshold vibration reduces postural sway magnitude and increases predictability.