Executive Project Summary

Timeline Summary:

At the beginning of the 2019-20 academic year, the team was tasked with the creation of a prototype biomedical device that will be used in on-going research to improve the quality and availability of cochlear implants. Today, cochlear implants are exclusively developed and manufactured by companies which utilize very expensive and complex multiple electrode technology, limiting the benefits of these devices to a relatively few people. Our client intended to demonstrate, with our assistance, that it is possible to obtain much better results than were previously gained using single electrode, inexpensive, fully analog cochlear implants.

The testbed had the following requirements: it should accept audio via microphone or auxiliary input and modulate that signal on an adjustable frequency sine wave. The modulated output should drive an external coil similar to current cochlear implants.

A majority of fall term was spent learning the scope of the project and the necessary background knowledge on cochlear implants. Our client did a fantastic job of providing documentation in order for the team to learn more about cochlear implants. The last few weeks of fall term were focused on the block diagram as the team began to define the scope of the project. At the start of winter term the team was unsure about certain aspects of our initial block diagram. Within the following weeks the team had the opportunity to meet face to face with their client and mentor. After the conversation the team was confident that the audio file management and signal modulation will be conducted in MATLAB, the modified audio file will then be uploaded onto an SD Card, a microcontroller will read from the SD Card and then transmit to the coil.

The middle and end of winter term was focused on the creation of our blocks and PCB design. Throughout the term, MATLAB and physical blocks were tested. The prototype PCB was built and tested. Results were not ideal, so we began correcting the PCB. The MATLAB UI provided straight forward user experience and gave the user many options when it came to testing different audio signals. Overall, at the end of winter term the team was confident that with modifications and further testing our testbed would achieve the objectives and goals of the project.

Looking Back and Results:

One project revision would focus on our DAC selection, which struggled to output at high frequencies due to communication protocol issues at high bitrates . Additionally, selecting a different microcontroller capable of faster serial communication may be worthwhile, as simultaneous communication with the SD card and DAC proved difficult. Due to issues with the power supply and an error in PCB trace routing we were unable to test the device in it's completed form. Unfortunately because of circumstances forcing OSU to e-campus for Spring term of 2020 we no longer had access to our design lab, and were unable to correct these issues.

Takeaways:

One key lesson from this project is to ensure you have a prototype and test components early enough in the design process. We waited until we were later in the design process to assemble and test our PCB and found several issues that needed correction. Earlier prototyping would have allowed us to catch these issues sooner in the process and revise the device accordingly.