Stowe Hammarberg

This project was in conjunction with designer Adriana Garcia and biomedical engineers Meghan Kaffine and Shahana Ganesharaja, advised by Dr. Shawn Kelly from the CMU Institute for Complex Engineered Systems.

 

We received a SURG grant from Carnegie Mellon to fund our work on the project, and were runners-up for the Johnson & Johnson Undergraduate Research Award after presenting it to judges.

Background: Dr. Shawn Kelly is working to develop a retinal prosthesis for patients blinded by retinitis pigmentosa or age-related macular degeneration. The prosthesis will help patients regain some vision by electrically stimulating the optic nerve. Once finalized, the implanted part of the prosthesis will need a source of video data, a processing unit, and a way to receive power. Our group worked on designing and prototyping a set of wearable external components that would provide these key resources to the implant. (Left: a model of Dr. Kelly's implant prototype)

Process: After discussions with Dr. Kelly and copious amounts of research into the science behind the diseases the device would address as well as the function of the implant, we established a 3-component external unit to make the device possible:

 

The Glasses contain a video camera and an inductive transmitter that would be used to wirelessly power and send data to the implant's induction coil. Adriana led the design of this component

 

The Brick is a battery pack and video processing device, connected to the glasses, supplying power and converting the raw camera data to a form usable by the implant. I led the design of this component

 

The Remote would be used to control the functions of the video processor, allowing features like digital zoom, edge recognition, and light sensitivity to be implemented. I also led the design of this component

Our first round of physical prototypes demonstrated the basic form factor of the device, with a waist-mounted brick connected via wire to the glasses, and the remote living partway up that wire, allowing access even if the cable and brick are covered by clothing.

I continued to refine the form of the brick and remote, focusing on using tactile cues to guide the user's hand when performing tasks such as controlling the image processing and plugging/unplugging the connector cable.

Our current model consists of three components:

• "glasses" with camera and inductive transmission coil

• cord mounted remote for controlling image processing modes

• circuitry and battery housing clipped to belt

The external coil and camera will be designed into a component that will be worn as a headpiece, similar to sunglasses. This component’s camera will capture the images, while the coil will communicate with the implant.

I also sought to emphasize the role of the device as a part of the user's body, avoiding the common "clinical" or grossly overdesigned appearances of many medical devices and leaning towards soft but stylish shapes

We also began designing our device around electronic components we were hoping to use to demonstrate some of the functionality it would have when paired with the implant.

A 4-button control on the cable allows the user to interact with the device (changing modes, zooming, requesting battery levels, etc).

The third component, clipped to the belt, will be responsible for processing the data through a  telemetry circuit designed by Prof. Kelly, and will enclose the battery used to power the entire external device and implant.

Glasses designed to house the camera module and an inductive charging coil

 

Controller pack of Raspberry Pi, battery pack, charging circuit, and video capture device. Above: a brick designed to compactly house these components

Final Prototype

The final glasses, with space for a camera module and inductive coil, as well as a hollow arm for wire routing

The final brick, scaled to house our prototype electronics, with tactile indications of orientation and charging/data port access. The design had to change significantly to minimize size on account of the rectangular circuit boards and batteries we used, but hopefully could be in a much more pleasing shape with Dr. Kelly's custom electronics.

Charging the device is achieved by unplugging the cable from the glasses and into a computer or this charging brick, which notifies the user when the device is connected, and the level of its battery when the top is pressed down.

Below are excerpts from the group's process work

The final remote prototype, with an easy grip and large button with strong feedback. Also modified to house off-the-shelf electronic switches.

Functionality

The glasses and the brick are connected via USB cable. This cord carries raw video data from the camera in the glasses to the brick, where it is processed and formatted  for the implant. The USB cord returns the video and power to the induction coil in the glasses.

 

 

The induction coil transmits video and power to the implant separately. The power current sent to the implant is very briefly interrupted; long enough to send data, but so briefly that the patient's vision isn't notably interrupted. A chip on the implant converts the data into a signal for the electrode array.

stowehammarberg@gmail.com

Stowe Hammarberg All content © 2016