Design of a Low Cost and Portable Wireless Near-infrared Spectroscopy System Using Embedded Linux

Near Infrared Spectroscopy(NIRS) is a non-ionizing and non-invasive technique that can be used to evaluate hemodynamic concentration in tissue. Wireless NIRS systems are useful for free-movement applications subject research, reducing movement artifacts and increasing subject comfort. Embedded Linux (EL) is an operating system used for a specific application; its use can reduce development time and cost. The goal of this project is to develop the first wireless NIRS system that utilizes EL. A BeagleBone Black development board is used with a deployed custom EL created with Yocto Project’s tools. The EL controls the two near-infrared LED sources, receives data from the two photo detectors amplified by a transimpedance amplifier, process/store and transmits via Bluetooth raw data. The data is displayed real-time on an Android cell phone. The signal to noise ratio of the system is assessed along with the battery life, its cost and size. The system is validated with an occlusion test in a subject arm. Ongoing development thus far allowed for minimal costs of US$ 140 and the device’s dimension of the current design is 9x5.5x2 cm, and its weight is about 100 grams. Comparing the cost of the proposed design with commercially available NIRS systems (from US$10,000 to US$100,000) we can assume that we can have a substantial reduction in prices in a commercial version of the proposed device. This low-weight device is smaller than most of commercially available wireless systems as well prototypes found in literature, this adds to comfort. Currently the proposed system only uses two sources and two detectors. Future work will include using this system as a co-modality with other techniques or imaging modalities, and to develop a system with more sources and detectors which will allow for increased spatial resolution.