Assistive Technologies for the Aging Population

The United States is experiencing an unprecedented growth of its older adult population from now until 2050. The current health paradigm, which is focused on the provider model of health, is not going to be able to handle this growth and demand on the system. A health model where patients and other stakeholders participate in healthcare may be sustainable. However, these people need to be empowered, and technology can play a big role. Thus, it will become of increasing importance to discover the most appropriate way to integrate technology into daily living to maintain proper quality of life for this adult cohort. The work contained in this doctoral dissertation is driven by the needs of older adults, and represents examples of the types of technologies and design methods that will be needed to keeping older adults healthy. These medical technologies aim to address some the prevalent healthcare issues facing older adults in an appropriate and dignity preserving way. Three technologies will be discussed here, the first is a novel hearing technology that addresses many of the concerns older adults have with the presently available hearing devices. The device is located deep in the ear canal and recreates sounds with mechanical movements of the tympanic membrane. The DHD successfully recreated ossicular chain movements across the frequencies of human hearing while demonstrating controllable magnitude. Moreover, the device was validated in a short-term human clinical performance study where the DHD successfully recreated sound in healthy subject.The second is an exploratory non-invasive diagnostic system that analyzes a subject's pupil light reflex to gain insight to neurological health. This prototype was developed and validated on a small population to evaluate the ease-of-use of this portable system and to establish a viable testing protocol to evaluate a population of retinal cells that are believed to be involved in a variety of neurological disorders. Lastly, a non-obtrusive insole was developed to measure a subject's balance and gait in many different environments. This technology has been designed and is currently undergoing testing in the department of Orthopedic Surgery at the University of California Irvine Medical Center

Assistive Technologies for the Aging Population

The United States is experiencing an unprecedented growth of its older adult population from now until 2050. The current health paradigm, which is focused on the provider model of health, is not going to be able to handle this growth and demand on the system. A health model where patients and other stakeholders participate in healthcare may be sustainable. However, these people need to be empowered, and technology can play a big role. Thus, it will become of increasing importance to discover the most appropriate way to integrate technology into daily living to maintain proper quality of life for this adult cohort. The work contained in this doctoral dissertation is driven by the needs of older adults, and represents examples of the types of technologies and design methods that will be needed to keeping older adults healthy. These medical technologies aim to address some the prevalent healthcare issues facing older adults in an appropriate and dignity preserving way. Three technologies will be discussed here, the first is a novel hearing technology that addresses many of the concerns older adults have with the presently available hearing devices. The device is located deep in the ear canal and recreates sounds with mechanical movements of the tympanic membrane. The DHD successfully recreated ossicular chain movements across the frequencies of human hearing while demonstrating controllable magnitude. Moreover, the device was validated in a short-term human clinical performance study where the DHD successfully recreated sound in healthy subject.The second is an exploratory non-invasive diagnostic system that analyzes a subject's pupil light reflex to gain insight to neurological health. This prototype was developed and validated on a small population to evaluate the ease-of-use of this portable system and to establish a viable testing protocol to evaluate a population of retinal cells that are believed to be involved in a variety of neurological disorders. Lastly, a non-obtrusive insole was developed to measure a subject's balance and gait in many different environments. This technology has been designed and is currently undergoing testing in the department of Orthopedic Surgery at the University of California Irvine Medical Center

A micro-drive hearing aid: a novel non-invasive hearing prosthesis actuator.

The direct hearing device (DHD) is a new auditory prosthesis that combines conventional hearing aid and middle ear implant technologies into a single device. The DHD is located deep in the ear canal and recreates sounds with mechanical movements of the tympanic membrane. A critical component of the DHD is the microactuator, which must be capable of moving the tympanic membrane at frequencies and magnitudes appropriate for normal hearing, with little distortion. The DHD actuator reported here utilized a voice coil actuator design and was 3.7 mm in diameter. The device has a smoothly varying frequency response and produces a precisely controllable force. The total harmonic distortion between 425 Hz and 10 kHz is below 0.5 % and acoustic noise generation is minimal. The device was tested as a tympanic membrane driver on cadaveric temporal bones where the device was coupled to the umbo of the tympanic membrane. The DHD successfully recreated ossicular chain movements across the frequencies of human hearing while demonstrating controllable magnitude. Moreover, the micro-actuator was validated in a short-term human clinical performance study where sound matching and complex audio waveforms were evaluated by a healthy subject

Completely-in-the-canal magnet-drive hearing device: a temporal bone study.

The magnet-drive hearing device (MHD) is a small completely-in-the-canal hearing aid prototype that drives the tympanic membrane (TM) through a magnetic interface. A cadaveric temporal bone was prepared. The MHD was coupled to a nickel-epoxy pellet glued to the umbo. Frequency sweeps between 0.3 and 10 kHz were performed, and the MHD was driven with various levels of current. Displacements of the posterior crus of the stapes were measured using a laser Doppler vibrometer and compared with sound-induced displacements. The MHD had a linear frequency response and low total harmonic distortion. The pellet placement altered the stapes movements; however, the changes were statistically insignificant. Inputs of 100 and 300 mV produced displacements equivalent to those of the natural sound at 70- and 80-dB sound pressure level, respectively. The coupling of this novel device using a magnetic interface to the umbo had a frequency output wider than air conduction devices, and its actuator was effective in driving the TM

Development of a novel completely-in-the-canal direct-drive hearing device.

Objectives/hypothesisTo develop a novel completely-in-the-canal device capable of directly driving the tympanic membrane (TM) and ossicular chain from the ear canal.Study designDevelopment and feasibility study.MethodsA voice coil actuator design was developed to drive the TM. Bench testing of the device using laser Doppler vibrometry (LDV) and sound recording was performed. Temporal bone studies using LDV were performed using different designs of the contact tip-TM interface to find the most efficient method of sound transmission. Two short-term clinical performance studies were performed using the latest 3-mm-wide device. Comparison was made to natural sound and to the Vibrant SoundBridge floating mass transducer simulator.ResultsOn bench testing, the device was found to have a low (<0.5%) total harmonic distortion in all frequencies above 400 Hz. Temporal bone studies revealed the device was capable of producing vibrations equivalent to 104 to 120 dB sound across most frequencies. The most efficient method of stimulation was when the device was coupled to the malleus. Short-term clinical performance studies indicated that pure tones and complex sound can be presented with the device. The sound quality of the experimental device was rated as better than the SoundBridge simulator device.ConclusionsThe direct-drive hearing device is capable of producing a wide range of sound frequencies and amplitudes. The device can transmit complex sound with low power requirements. Further work on the development of the device is needed for long-term and wider clinical use.Level of evidenceNA Laryngoscope, 127:932-938, 2017

Development of a novel completely-in-the-canal direct-drive hearing device.

Objectives/hypothesisTo develop a novel completely-in-the-canal device capable of directly driving the tympanic membrane (TM) and ossicular chain from the ear canal.Study designDevelopment and feasibility study.MethodsA voice coil actuator design was developed to drive the TM. Bench testing of the device using laser Doppler vibrometry (LDV) and sound recording was performed. Temporal bone studies using LDV were performed using different designs of the contact tip-TM interface to find the most efficient method of sound transmission. Two short-term clinical performance studies were performed using the latest 3-mm-wide device. Comparison was made to natural sound and to the Vibrant SoundBridge floating mass transducer simulator.ResultsOn bench testing, the device was found to have a low (<0.5%) total harmonic distortion in all frequencies above 400 Hz. Temporal bone studies revealed the device was capable of producing vibrations equivalent to 104 to 120 dB sound across most frequencies. The most efficient method of stimulation was when the device was coupled to the malleus. Short-term clinical performance studies indicated that pure tones and complex sound can be presented with the device. The sound quality of the experimental device was rated as better than the SoundBridge simulator device.ConclusionsThe direct-drive hearing device is capable of producing a wide range of sound frequencies and amplitudes. The device can transmit complex sound with low power requirements. Further work on the development of the device is needed for long-term and wider clinical use.Level of evidenceNA Laryngoscope, 127:932-938, 2017

Completely-in-the-Canal Magnet-Drive Hearing Device

The magnet-drive hearing device (MHD) is a small completely-in-the-canal hearing aid prototype that drives the tympanic membrane (TM) through a magnetic interface. A cadaveric temporal bone was prepared. The MHD was coupled to a nickel-epoxy pellet glued to the umbo. Frequency sweeps between 0.3 and 10 kHz were performed, and the MHD was driven with various levels of current. Displacements of the posterior crus of the stapes were measured using a laser Doppler vibrometer and compared with sound-induced displacements. The MHD had a linear frequency response and low total harmonic distortion. The pellet placement altered the stapes movements; however, the changes were statistically insignificant. Inputs of 100 and 300 mV produced displacements equivalent to those of the natural sound at 70- and 80-dB sound pressure level, respectively. The coupling of this novel device using a magnetic interface to the umbo had a frequency output wider than air conduction devices, and its actuator was effective in driving the TM

A micro-drive hearing aid: a novel non-invasive hearing prosthesis actuator

The direct hearing device (DHD) is a new auditory prosthesis that combines conventional hearing aid and middle ear implant technologies into a single device. The DHD is located deep in the ear canal and recreates sounds with mechanical movements of the tympanic membrane. A critical component of the DHD is the microactuator, which must be capable of moving the tympanic membrane at frequencies and magnitudes appropriate for normal hearing, with little distortion. The DHD actuator reported here utilized a voice coil actuator design and was 3.7 mm in diameter. The device has a smoothly varying frequency response and produces a precisely controllable force. The total harmonic distortion between 425 Hz and 10 kHz is below 0.5% and acoustic noise generation is minimal. The device was tested as a tympanic membrane driver on cadaveric temporal bones where the device was coupled to the umbo of the tympanic membrane. The DHD successfully recreated ossicular chain movements across the frequencies of human hearing while demonstrating controllable magnitude. Moreover, the micro-actuator was validated in a short-term human clinical performance study where sound matching and complex audio waveforms were evaluated by a healthy subject