Assistant Professor Rowan University, United States
Introduction: Hearing loss affects over 400 million people, including at least 34 million children. A significant number of these children are diagnosed with conductive hearing loss (CHL), which occurs when sound waves cannot efficiently pass through the outer or middle ear due to issues such as fluid buildup, ear infections, or structural abnormalities in the ear.
Most current treatment options for CHL involve surgical procedures, which are often intimidating and risky, especially for pediatric patients. Non-invasive treatments like bone-conduction hearing aids exist, but they are typically bulky and uncomfortable for children. Our design addresses these issues by constructing the hearing aid on flexible printed circuit boards (PCBs) encapsulated in polydimethylsiloxane (PDMS). This approach enhances comfort and allows the device to conform better to the child's head, improving sound conduction. Although the device is flexible, it remains unstretchable and sturdy for daily use
Our innovative design aims to provide a comfortable and effective non-invasive solution for pediatric patients with CHL, potentially reducing the need for surgical interventions and associated costs.
Materials and
Methods: Peel Tests:
Setup: Adhesives were applied to both acrylic and skin substrates. The setup involved securing one end of the adhesive to a stationary acrylic substrate while attaching the other end to a force sensor. Testing: A force sensor was used to hold the adhesive from opposite ends and gradually pull it apart until it detached from the surface. The force applied was recorded throughout the test to determine the adhesive strength. Data Collection: The force required to peel the adhesive from the surface was measured and analyzed to compare the performance of different adhesives.
Vibration Measurements:
Objective: To evaluate the impact of different adhesives on the performance of the PZT (piezoelectric transducer) in terms of vibration transmission. Procedure: Adhesives were tested by applying them to the PZT and measuring the resultant vibrations using a vibrometer. The setup involved securing the PZT with the adhesive and subjecting it to a standard vibration source. Data Collection: The vibrations transmitted through the PZT were recorded and analyzed using a laser Doppler vibrometer (LDV) to determine the effectiveness of each adhesive in maintaining optimal vibration levels.
Results, Conclusions, and Discussions: Peel Test Comparisons:
Plastic Substrates: The peel test on plastic substrates revealed that Miilye adhesive had the highest maximum peak load of 23 N. Skin Substrates: Comparing 3M’s Transpore and Nexcare adhesives on skin, Nexcare exhibited the smallest maximum peak load, making it gentler on the skin with a peel force of 0.73 N. This minimizes the risk of skin injury when the hearing aid is removed.
Vibration Analysis:
The velocity of vibrations produced by the actuator was measured when secured with different adhesives. Nexcare tape allowed the actuator to achieve a peak velocity of 7 mm/s and an average velocity of 3.4 mm/s, indicating superior vibration transmission to the cochlea compared to Transpore and Equate tapes.
Substrate Modifications:
PDMS Molding: Using 3D printed molds, we successfully standardized the production of flexible PDMS substrates, demonstrating their moldability and suitability for flexible circuitry. Conductive Channels: An optimal weight ratio of 45:55 for graphite was identified, ensuring effective conductivity and integration of circuit components into the PDMS.
Acknowledgements (Optional): Data collection was made possible with the assistance of my lab partners: Raaha Kumaresan, Michael DeMelas, and Joseph Rosa. This project was funded by Rowan University and the National Institutes of Health, National Institute on Deafness and Other Communication Disorders under Award R21DC018894.
