3D printed smart transtibial prosthesis equipped with temperature and pressure sensory systems

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Abstract

Integration of the sensory systems inside patient-specific medical devices (e.g., implants or prosthesis) can provide additional measurement data at different time points. This can result in improving the traditional designs of those medical devices, and consequently leading to increasing the patient’s comfort and quality of life. By doing measurements directly on or inside the patient, information can be gathered more specifically, which is important for improving detection and diagnosis. Next to that, it enables better decision-making for therapies, treatments and the allocation of prosthesis, causing improved rehabilitation. Problems with the comfort and fitting of the prosthesis can have a big impact on the life of the patient wearing the prosthetic. If there is lack of comfort, the patient is less likely to wear the device and that could limit the rehabilitation and satisfaction about their life in multiple areas. To get a better insight in the transtibial prosthesis in particular, and possibly solve the problems that occur, measurements can be done at the interface of the patient and the socket of this prosthesis. The data can be used to visualize the problem more accurately and, as a result, the response and treatment process can be chosen in a more precise manner. First, a case study about the lower limb prosthesis was conducted. Several questions will be reviewed, including defining elements of the satisfaction of patients about their prosthesis, what current existing problems with prosthesis are and the reasons of patients why they are not satisfied with their prosthesis. Then, two types of sensors will be used to visualise the problems occurring at the interface of the socket and the residual limb. One type of sensor is the piezoelectric pressure sensor. It is used to map the pressure on the limb inside the socket. Several experiments have been done with an existing 3D printed socket design and the data is compared to a finite element model that predicts stress distributions to validate this model. The model itself was changed on multiple areas to get closer to test conditions and improve model outputs. To be able to improve such models, the test-procedure should be further revised. After that, thermistors were used to measure the temperature within a 3D printed socket. A design for a new socket has been made to actively use the temperature data and cool the residual limb inside the socket when needed. This is done by integrating air-channels within the structure of the 3D printed socket and air is forced through those channels with a power-fan. The design has been validated with several tests and it is improved based on that. Those tests, calculations and estimations have shown that the current design may be able to cool the residual limb when further improved and optimized. In the end, several suggestions and recommendations for improvements were provided. Some of those improvements could be made in the size of the air-channels and the interface between socket and residual limb. Finally, present and potential (ongoing) developments on how to change the patient's condition, as well as how to apply promising developments in innovative ways, will be addressed.