Through our research and conversations with people living with tremor, we know that forcibly suppressing a person’s tremor can cause pain and discomfort. We developed a uniquely effective and compact device that uses active tremor cancellation to 1) reduce the amount of force we need to counteract and 2) implement a control system that can quickly filter out unintentional tremor while preserving intentional hand movement. Overcoming the forces generated by a trembling hand or arm typically requires large, awkward structures such as braces or weights. We were able to miniaturize LiftWare relative to other technologies by inventing a system that stabilizes only the bowl of the spoon, requiring much less force than a system that suppresses hand tremor. And by allowing the hand to tremor, using LiftWare feels natural and is comfortable to use.
Since we aren’t forcing the hand to be still, we needed a technology that could respond quickly to a person’s tremor, and also tell the difference between intentional motion (such as moving the spoon to your mouth) and unintentional tremor. Sensors embedded in the spoon detect motion, and a microcontroller uses sensor data to determine the best response. The microcontroller continuously directs motors in the handle of the device to move the spoon and cancel tremor both horizontally and vertically. Since we know that almost all Essential and Parkinsonian Tremor occurs between 4 and 7 cycles per second, we optimized our control system to only cancel motion in that range. As a result, food is kept steady in the bowl of the spoon through our active tremor cancellation technology.
The video clip shown above illustrates the effectiveness of a very early device working in the lab. The prototype is filled with granola while attached to an apparatus that simulates tremor. You can see that with the system turned off, the granola will immediately fly out of the bowl of the spoon, while turned on the granola is held indefinitely.
The next step was to test our prototype device in some controlled human subject testing (this was part of a program funded by the NIH). For those who are interested, an abstract of our clinical trial can be found here. Briefly, we were able to measure a cancellation of greater than 70%, and you can see the dramatic difference that the active cancellation makes for the patients. It takes a little bit of adjustment to get used to the "floating" nature of the spoon, but most were able to adapt pretty quickly.
Human Subject Testing.
We've come a long way since our clinical trials, and have focused on engineering design. Our final product is now available (more details here), and we're already working on more applications. Stay tuned!