More than 80% of Americans will experience back pain in their lifetime, and much of this is due to poor posture. Sitting improperly at work is the worst culprit, so to combat this problem we created the Biofeedback Posture Chair. By combining biofeedback technology with an ergonomic chair, we are able to detect and correct posture with a mobile app that gives users feedback on their sitting positions. We custom contoured an office chair by tracing the user's spine, so that each chair is the perfect fit for the user. In doing this, we are able to reinforce the ideal sitting position for any user, regardless of height or back curvature. We then fixed force sensors onto the back to ensure that the user is sitting with even pressure throughout the chair to prevent slouching. Then, the user can see the data of their posture displayed both in graph form, as well as detection of the pressure of each point. This way the user can not only visualize their posture, but they can get real time feedback to fix it. In the future we are planning to add alert features, so that the user can be notified of poor posture even when the app is closed. We will use push notifications to give posture alerts, as well as alerts for long periods of sitting to encourage users to take walks and get regular physical activity. In the end the goal is not just to improve posture, but support an overall healthy lifestyle.

To create this chair we took a photo of the user in tight fitting clothing, sitting up straight, with a ruler for scale. We then used the curve derived from this process as the basis for our ergonomic chair. We then CNC milled the back of the chair, as well as a comfortable base, out of hard foam and lasercut a wood backing for stability. We then attached 6 force sensors to the back, putting a left and right sensor on the top, middle, and bottom contact points. This data was sent to the computer using an arduino, and then we processed the data in processing and sent it to our server. Then, we created an iPhone app that downloads the data from the server and creates a graphic visualization so the user can view and correct their posture. 

We now have a fully functional final product, but it took several iterations to get here. We originally were not going to custom contour the back, but we planned to have three inflatable cushions that could adjust to the user’s spine. This proved to be problematic, since the inflatable cushions give unreliable readings for the force sensors. We then moved on to custom contouring, but the original chair back was just the curve swept over half an ellipse. This ended up being somewhat comfortable, but it did not make full contact with the back. We then decided to map our back curve over a complex model of a chair, based off of an ergonomic chair we already owned, but with the vertical curve replaced. This ended up being perfect, as it hugged the back on all sides and made full contact with the sensors.