SmartCast: Instrumented Casts for Monitoring and Intervention during Bone Healing Process

Orthopedic casts are the typical procedure for treatment of bone fractures because they stabilize the broken bone and allow proper healing to occur. Such a device is put on when tissue inflammation due to injury is very high. However, as the healing process begins and swelling subsides, the cast is no longer a sturdy fit and hence the bone might heal improperly. Putting the bone back in position, which in some cases may necessitate re-fracturing and re-aligning the bone is a very painful and expensive procedure.The SmartCast system was developed to address this problem and create a solution to detect inflammation reduction beyond a certain threshold. At this stage, the cast requires physician's attention. The system consists of a network of pressure sensitive sensors that are sewn on a sleeve worn under the cast. The sensors are connected to a case for information extraction and processing using 8 conductive threads. The case includes a printed circuit board, power supply, and an SD memory card. The current system output is the resistance characteristic of the sensors as a function of pressure, giving an indication of the swelling level in the tissue. Experiments with several sensor types were conducted to determine state of contact between skin and inside of the cast. This thesis focuses on several aspects of the design and development of SmartCast, namely (1) design of cast's embedded platform, (2) development of the electronic circuit to interact with the sensors, (3) consideration of proper size and fit, and (4) design for manufacturability and ease of use