Multimodal Portable Functional Brain Imaging Chip

Abstract

Near-infrared spectroscopy is a non-invasive technology that uses source-detector pairs for measuring bio-signals such as hemodynamics. Continuous-wave near-infrared spectroscopy(CWNIRS) was widely used for signal measurement due to its simple implementation and system portability. However, this method is not suitable for absolute optical property measurement which is critical to deriving accurate tissue property. Frequency-domain NIRS(FDNIRS) and time-domain NIRS(TDNIRS) are solutions for this problem. FDNIRS operates at high speed compared with CWNIRS, which increases its hardware complexity. To solve the system bulkiness, an integrated circuit system design was implemented for FDNIRS. Fabricated FDNIRS IC used a delay-locked loop (DLL) and a low sampling rate analog-to-digital converter (ADC) to extract amplitude and phase delay information of the NIRS signal. IC system realizes a portable, real-time measurement system.