Microcontroller-based digital front-end for near-infrared spectroscopy

Giardini, Mario Ettore and Corti, Mario and Guizzetti, Giovanni G. and Lago, Paolo and Gelmetti, Andrea and Danese, Giovanni; Vo-Dinh, Tuan and Grundfest, Warren S. and Benaron, David A., eds. (2000) Microcontroller-based digital front-end for near-infrared spectroscopy. In: Diagnostic, Guidance and Surgical-Assist Systems II. Proceedings of SPIE . SPIE, USA, pp. 338-344. ISBN 0819435279 (https://doi.org/10.1117/12.384921)

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Near Infrared Spectroscopy (NIRS) can be employed to noninvasively and continuously measure in-vivo local changes in haemodynamics and oxygenation of human tissues. Monitoring of these parameters is particularly useful both for basic research and during surgery, when a continuous and real-time measurement can help to avoid permanent damage to the tissues. We present a modular acquisition system in which each subsystem, from the case to the single acquisition front-end is designed to meet all the requirements of a research-grade instrument, dedicated to intraoperatory measurements. Part of the modules of the acquisition system has been dedicated to multipoint NIRS. A module prototype has been developed, which is able to control four LED sources and two detectors. On each front-end a RISC microcontroller performs source and detector multiplexing with a digital correlation technique. A number of such modules can be independently addressed through a bus by a PC-based workstation (integrated on the instrument) for data collection, processing and visualization. Preliminary tests of the prototype on tourniquet-induced forearm ischaemia show adequate detectivity and time response. The operating parameters derived from the prototype will be employed in the design of a high channel count module, which will exploit the capabilities of a digital signal processor (DSP), for spatially mapped brain oxygenation monitoring.