Time Domain NIRS Optode based on Null/Small Source-Detector Distance for Wearable Applications

Saha, Sreenil; Burri, Samuel; Bruschini, Claudio; Charbon, Edoardo; Lesage, Frédéric

doi:10.1109/cicc.2019.8780320

Cited by 7 publications

(10 citation statements)

References 28 publications

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“…It allowed the use in direct contact with the tissue under investigation, avoiding the use of cumbersome optical fibers and increasing the signal collection thanks to the large numerical aperture of the detector (approaching 1) [61]. In the following years, other researchers in the world started to work on similar concepts to develop their own compact TG devices and optodes based on dummy signal generation [96][97][98][99][100]. In these cases, the TG detector active area has a diameter of few ~10 µm, limiting the collection capability of diffused light [100].…”

Section: State Of the Artmentioning

confidence: 99%

“…This increase will result in the possibility of computing the contrast produced by a localized perturbation at much later times along the recorded DTOF thanks to the increased collection of late photons, thus enhancing the depth sensitivity. To this purpose, SiPMs have been recently introduced in TD-DO [103][104][105][106] giving rise to a new generation of devices [100,106,107]. SiPMs are large-area microelectronics single-photon detectors based on multiple SPADs, each one with an integrated quenching resistor, with a common output signal.…”

Section: Detector Active Areamentioning

confidence: 99%

“…One of the main fields of application of the TG technique is the brain functional imaging. Indeed, the use of the small ρ approach coupled to the time gating technique allows to increase the mean penetration depth and to realize small probes [100]. This peculiarity opens different research lines from the diagnosis/monitoring of patients' health to the consumer market.…”

Section: Functional Imagingmentioning

confidence: 99%

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Time-Gated Single-Photon Detection in Time-Domain Diffuse Optics: A Review

Mora

Sieno

et al. 2020

Applied Sciences

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This work reviews physical concepts, technologies and applications of time-domain diffuse optics based on time-gated single-photon detection. This particular photon detection strategy is of the utmost importance in the diffuse optics field as it unleashes the full power of the time-domain approach by maximizing performances in terms of contrast produced by a localized perturbation inside the scattering medium, signal-to-noise ratio, measurement time and dynamic range, penetration depth and spatial resolution. The review covers 15 years of theoretical studies, technological progresses, proof of concepts and design of laboratory systems based on time-gated single-photon detection with also few hints on other fields where the time-gated detection strategy produced and will produce further impact.

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Section: State Of the Artmentioning

confidence: 99%

Section: Detector Active Areamentioning

confidence: 99%

Section: Functional Imagingmentioning

confidence: 99%

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Time-Gated Single-Photon Detection in Time-Domain Diffuse Optics: A Review

Mora

Sieno

et al. 2020

Applied Sciences

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“…Other works presented in literature use actively gated detectors, but operated only in photon-counting mode, with no information on the photon arrival time within the gate [14], [20], [22], [23]. In such approaches, by shifting the gate position with respect to the excitation laser and acquiring multiple measurements, low temporal resolution waveforms can be acquired, but the measurement time is increased if the incoming photon flux is very low.…”

Section: Gating Operationmentioning

confidence: 99%

“…On the other hand, analog silicon photomultipliers (SiPMs) have been used in wearable probes, lacking time-gating capability but gaining more than 1 order of magnitude in terms of active area size, enabling their use only at large source-detector separations (i.e., >2 cm). The combination of these features would be highly beneficial in TD-NIRS [1], but it is challenging and the only attempt reported so far in literature has been done by placing side by side a time-gated SPAD and an analog SiPM [14]. However, in such configuration, the SPAD remains photon-starved and the SiPM can only operate at large source-detector separations.…”

mentioning

confidence: 99%

Large-Area, Fast-Gated Digital SiPM With Integrated TDC for Portable and Wearable Time-Domain NIRS

Conca

Sesta

Buttafava

et al. 2020

IEEE J. Solid-State Circuits

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We present the design and characterization of a large-area, fast-gated, all-digital single-photon detector with programmable active area, internal gate generator, and time-todigital converter (TDC) with a built-in histogram builder circuit, suitable for performing high-sensitivity time-domain nearinfrared spectroscopy (TD-NIRS) measurements when coupled with pulsed laser sources. We used a novel low-power differential sensing technique that optimizes area occupation. The photodetector is a time-gated digital silicon photomultiplier (dSiPM) with an 8.6-mm 2 photosensitive area, 37% fill-factor, and ∼300 ps (20%-80%) gate rising edge, based on low-noise single-photon avalanche diodes (SPADs) and fabricated in 0.35-µm CMOS technology. The built-in TDC with a histogram builder has a least-significant-bit (LSB) of 78 ps and 128 time-bins, and the integrated circuit can be interfaced directly with a low-cost microcontroller with a serial interface for programming and readout. Experimental characterization demonstrated a temporal response as good as 300-ps full-width at half-maximum (FWHM) and a dynamic range >100 dB (thanks to the programmable active area size). This microelectronic detector paves the way for a miniaturized, stand-alone, multi-wavelength TD-NIRS system with an unprecedented level of integration and responsivity, suitable for portable and wearable systems. Index Terms-Digital silicon photomultiplier (dSiPM), fastgated single-photon avalanche diode (SPAD) array, photon counting, time-to-digital converter (TDC), time-domain near-infrared spectroscopy (TD-NIRS). I. INTRODUCTION T IME-DOMAIN near-infrared spectroscopy (TD-NIRS) is a powerful technique for obtaining non-invasive, in vivo measurements of tissue constituents and structure [1]. This can be exploited in many scientific fields, from a clinical Manuscript

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