33.10 A 2.7ps-ToF-Resolution and 12.5mW Frequency-domain NIRS Readout IC with Dynamic Light Sensing Frontend and Cross-Coupling-Free Inter-Stabilized Data Converter

The non-invasive quantification of metabolite concentration is of significant importance in the fields of medical diagnosis and monitoring. Functional near-infrared spectroscopy (NIRS) offers a promising optical solution for this purpose. However, conventional continuous-wave (CW) NIRS systems only record light intensity, limiting analysis of optical absorption (μ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</inf> ) and reduced scattering (μ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</inf> ') coefficient fluctuations in substances [1–2]. This hinders obtaining absolute metabolite concentrations, limiting the technology's utility. Frequency-domain (FD) NIRS emits intensity-modulated light into human tissues, allowing simultaneous measurement of changes in optical intensity loss and light time-of-flight (ToF). It then determines absolute metabolite concentrations,.addressing key needs in brain functional imaging, drug metabolism studies and cancer diagnosis.