Silicon photomultiplier based continuous-wave functional near-infrared spectroscopy module with multi-distance measurements

In recent years, there has been growing interest in developing fiberless and wireless functional near-infrared spectroscopy (fNIRS) and diffuse optical tomography (DOT) instruments. However, developing such instruments poses multiple challenges, interms of cost, safety, system complexity and achievable signal quality. One crucial factor in developing wireless and fiberless instruments is the appropriate choice of detectors. Currently, the majority of existing wireless and/or fiberless systems use photodiodes due to their low cost and low power requirements. However, under low-light conditions, the SNR of photodiodes diminishes significantly, making them less effective for measurements with long source–detector separations. The silicon photomultiplier (SiPM) is a relatively new type of detector that contains high internal amplification; this makes SiPMs suitable for low-light applications. Although SiPMs can increase signal quality at long source–detector distances, they cost more and have higher power requirements than photodiodes. This thesis presents the design of a multi-distance, multichannel DOT prototype that uses a hybrid detector arrangement. This arrangement uses photodiodes for short-distance measurements (i.e., 1 cm) and silicon photomultipliers for long-distance measurements (i.e., 3 cm and 4.5 cm). The developed system consists of two printed circuit boards (PCBs): a DOT sensor PCB, a data acquisition and control PCB as well as a graphical user interface. The performance of the developed DOT system prototype was validated using a dynamic optical phantom. The results show that the prototype works as intended

Knee Angle Measurement System for Knee Implants

The goal of this thesis project is building a knee angle measurement system for knee implants. Measuring the knee angle can be the new postoperative diagnosis method which assists in early diagnosis of total knee implants (TKAs). This system is used to acquire magnetic field data from magneto sensors and process it using a microcontroller. Then, this data is transmitted wirelessly in to a receiver system (data logger) which logs the received data into a computer or USB. The work was carried out in two phases. First, the work of previous students was modified and optimized. After this the analog magneto sensors were replaced with digital sensors, and the analog frontend ADS1296 (AFE) was omitted, resulting in a smaller and cheaper PCB. Finally, it was possible to develop a system which can measure the magnetic field variation, which is dependent on the position of magnet and transmit it wirelessly via a wireless transmitter. Further work can be done to modify this project by processing the sensor data acquired and associate it with the exact location of the magnet. Another possibility of further work is modifying the PCB further by using a microcontroller with an embedded wireless module such as CC430 by Texas Instruments