title: Probe-hosted silicon photomultipliers for time-domain functional near-infrared spectroscopy: phantom andin vivotests.
abstract: We report the development of a compact probe for time-domain (TD) functional near-infrared spectroscopy (fNIRS) based on a fast silicon photomultiplier (SiPM) that can be put directly in contact with the sample without the need of optical fibers for light collection. We directly integrated an avalanche signal amplification stage close to the SiPM, thus reducing the size of the detection channel and optimizing the signal immunity to electromagnetic interferences. The whole detection electronics was placed in a plastic screw holder compatible with the electroencephalography standard cap for measurement on brain or with custom probe holders. The SiPM is inserted into a transparent and insulating resin to avoid the direct contact of the scalp with the 100-V bias voltage. The probe was integrated in an instrument for TD fNIRS spectroscopy. The system was characterized on tissue phantoms in terms of temporal resolution, responsivity, linearity, and capability to detect deep absorption changes. Preliminaryin vivotests on adult volunteers were performed to monitor hemodynamic changes in the arm during a cuff occlusion and in the brain cortex during a motor task.
authors.affiliation: Politecnico di Milano , Dipartimento di Fisica, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Re
authors.affiliation: Politecnico di Milano , Dipartimento di Fisica, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Martinenghi
authors.affiliation: Politecnico di Milano , Dipartimento di Fisica, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
authors.forename: Alberto Dalla
authors.initials: AD
authors.lastname: Mora
authors.affiliation: Politecnico di Milano , Dipartimento di Fisica, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Contini
authors.affiliation: Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo da Vinci 32, Milano 20133, Italy; Consiglio Nazionale delle Ricerche, Istituto di Fotonica e Nanotecnologie, Piazza Leonardo da Vinci 32, Milano I-20133, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pifferi
authors.affiliation: Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo da Vinci 32, Milano 20133, Italy; Consiglio Nazionale delle Ricerche, Istituto di Fotonica e Nanotecnologie, Piazza Leonardo da Vinci 32, Milano I-20133, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Torricelli
keywords: detector; near-infrared spectroscopy; time domain