Arthritis affects 40 million Americans today. It is the inflammation of a joint cavity and results in mobility reduction and constant pain for those who suffer from it. Throughout an arthritis patient’s recovery, rheumatologists prescribe treatment plans to minimize joint inflammation. Treatment efficacy can only be assessed in person and requires an experienced health professional. This dramatically limits the frequency of joint health assessment, elongating the treatment evaluation period and increasing the risk for irreversible joint damage. To address this, we have built Sentrac, a monitoring device that can allow a patient to independently and consistently measure joint volume to track inflammation in the knee at home.
Sentrac is a wrap device worn on the knee and could offer patients the ability to track joint inflammation remotely. The wrap is composed of a silicone front with embedded liquid metal galinstan strain sensors that can detect and quantify stretch. The wrap is attached with a buckle mechanism and Velcro. The device has Bluetooth and pairs with a web application that allows patients to visualize and track their joint inflammation.
The device was tested in two ways: resolution and repeatability. Both were done using a machine that could accurately pull the device to know distances. The tests were to repeatedly pull the device to a fixed length, which resulted in a Cronbach’s alpha of 0.77, which shows good reliability. The device was also pulled to know lengths between 0-2 inches, in 0.67 increments, 60 times (estimated usage in 5 years) and the error of the device reading to the know distance was determined to be 2.5mm. This means the device was in the 5mm range required for successful measurement. These results show that Sentrac has the potential to revolutionize arthritis treatment assessment with reliable and repeatable measurements.