Broad-bandwidth frequency-domain near-infrared spectroscopy system on a chip

Frequency-domain near infrared spectroscopy (fd-NIRS) is used to noninvasively characterize in vivo tissue structure and molecular composition by exploiting the deep tissue penetration of red and near-infrared light. However, the size, complexity, expense, and lack of scalability of current fd-NIRS hardware has slowed its translation to clinical applications. Here we present a broad-bandwidth 1.2 x 1.2 mm fd-NIRS application-specific integrated circuit that represents a critical step toward ultrasmall, easily scalable, and wearable fd-NIRS. We present the fd-NIRS integrated circuit design as well as results showing its optical property measurements are comparable to those measured with a standard reference system.