A CMOS Sensor for Measurement of Cerebral Optical Coefficients Using Non-Invasive Frequency Domain Near Infrared Spectroscopy

Abstract

A heterodyned architecture is integrated with a 180 nm CMOS chip for use in portable frequency domain near infrared spectroscopy (fdNIRS) tools for real time monitoring of tissue oxygenation in the brain. The design and performance measurement results of this chip are summarized in this paper to demonstrate its applicability in multi-distance fdNIRS to measure the absorption and scattering coefficients of tissue. The 2.25 mm 2 chip is integrated with four sensor channels, which have a high frequency low noise front end and information processing circuitry to interface with an avalanche photodiode to detect the high speed weak light signal. The four-channel sensor draws 40 mA of current from a 1.8 V power supply and uses an offchip counter implemented on an FPGA to quantify the amplitude and phase information required for tissue characterization with < 6.5% and < 2.5% linearity error, respectively. An experiment using the multi-distance measurement is used to measure the optical properties of a homogeneous tissue phantom using the CMOS integrated instrument.Index Terms-Frequency domain near infrared spectroscopy, CMOS, transimpedance amplifier, amplitude and phase detection, amplifier noise, optical sensor.

Design of a miniaturized frequency domain near infrared spectrometer with validation in solid phantoms and human tissue

“…The accuracy of our instrument and previously reported fdNIR systems are compared in Table 2. 8,9,11,[14][15][16] We can see that our design achieved a good level of accuracy among the other reported systems. Especially considering the fact that our system if at least an order of magnitude smaller than systems of accuracy below 15% as well as avoiding the use of expensive (even more so than the complete commercial fdNIR instrument from ISS) and complex equipment such as a vector network analyzers (VNAs), standalone laser controller/drivers or very high speed ADCs that require an field programmable gate array development kit.…”

“…The systematic errors such as validity of semi-infinite medium assumption, uneven light coupling, and variation in probe fabrication can be minimized by applying more sophisticated calibration and correction methods. 14…”

“…The systematic errors such as validity of semi-infinite medium assumption, uneven light coupling, and variation in probe fabrication can be minimized by applying more sophisticated calibration and correction methods. 14 Accuracy. To characterize the accuracy of fdNIR instruments, usually measurements on solid and/or liquid phantoms with known optical parameters are conducted.…”

Vertical-cavity surface-emitting laser sources for gigahertz-bandwidth, multiwavelength frequency-domain photon migration

“…Additional major components include an optical detector and the electronics necessary to extract and transmit the time-resolved signals. Miniaturized integrated circuits to perform processing of FDPM data have already been demonstrated; 36 , 37 however, detector miniaturization remains a challenge. Silicon-based APDs and photomultiplier tubes, common choices for FDPM measurements, both require a high voltage bias (>100 VDC) to achieve the required gain/sensitivity.…”

Frequency-Domain Techniques for Cerebral and Functional Near-Infrared Spectroscopy

“…Recent developments in FD-NIRS instrumentation include implementations based on a compact frequency-sweeping circuit board (No et al, 2008), digital heterodyning (Arnesano et al, 2012), direct digital sampling (Roblyer et al, 2013;Zimmermann et al, 2016), frequency division multiplexing (Torjesen et al, 2017;Zhao et al, 2018), CMOS integrated circuitry (Sthalekar and Joyner Koomson, 2013;Yun and Joyner Koomson, 2013), and vertical cavity surface emitting lasers (VCSEL) (Sultan et al, 2013;Kitsmiller et al, 2018).…”