The project started with the development of a specific type of sensor which is the foundation of the SocketMaster system. The sensor unit was able to measure multiple biomechanical parameters that are crucial to the comfort of a patient wearing a socket.
Afterwards, the sensor unit was further assembled as sensor pad, where a micro motor was connected to control the movement of the pad within a mechanical frame of a Master Socket.
To ensure different posture can be simulated during testing, a loading apparatus was also designed and fabricated. The integrated SocketMaster hardware system, which comprised of a gait loading apparatus and a Master Socket.
The control software of the SocketMaster system is composed of different modules that have been built based on the system architecture . The data collector board uses I2C communication protocol to talk with motors and sensors installed on the socket.
A well-fitting socket requires to take into account the biomechanical property of soft tissue of a patient’s residual limb. To this end, a hand-held device was developed.
During clinical test, the collected data was used for socket design. A Solidworks based approach has been established which generates 3D shape of the stump and then a socket. This approach requires comprehensive manual operations between coordinates, line, curves and 3D shapes. It starts from the coordinate’s matrix of the 47 sensors, and the shape of the entire socket has been reconstructed in a unique model. For the patients with a short stump, the coordinates of the lower ring were not considered because this ring was not in contact with the leg. A physical model that has been fabricated using FDM (Fused Deposition Modelling) Type 3D printing with PETG. It demonstrated that this SolidWorks based socket design approach is working.
The fist clinical trial was performed on a pilot patient in May 2017 at the London Prosthetic Centre (LPC). The test revealed a number of issues that need to be improved for further clinical tests. It took nearly a year to complete the re-assembly of the Master Socket, including software integration. The second clinical trial was conducted in early May 2018 in Greece, then the updated system was shipped to LPC in London again in early May 2018. 14 clinical tests where biomechanical data were recorded had been done on six trans-femoral amputee patients by the end of the project.
The six subjects who participated in clinical trials have an age ranging from 38 to 75 years. They include 2 males and 4 females, 2 left leg and 4 right leg that had been amputated. Some of the subjects participated in the tests on multiple days, with multiple trial tests for consistency analysis.
The clinical test started with the initialization of the micro motors and the loading apparatus, followed by a manual adjustment of the system according to the patient’s biometric characteristics. Afterwards, the system was worn by the patient, and every part was fine-tuned such that the patient felt at an optimal comfort with the Master Socket. Biomechanical data from the 47 sensors were collected and saved in the control laptop. All the biomechanical data were analysed offline, which showed that the sensors provided consistent measurement results. The positional data of the sensor pads and the brim parts were fed into the Socket Master Geometry Maker module. Together with the data of manual adjustments of the brim parts, and a CAD file for a check socket can be produced by using SolidWorks for manufacturing (e.g. 3D printing).
