Silicon Integrated Circuits and Systems for Frequency Domain Near Infrared Spectroscopy.
Sthalekar, Chirag.
2015
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Abstract: The design
and measurement details of a silicon integrated frequency domain near infrared
spectroscopy (fdNIRS) sensor system are presented in this work. fdNIRS is used to
non-invasively measure absolute tissue hemodynamics. This can be used to indicate the
presence of tumors, measure brain function, in- dicate stress levels and tissue health
by non-invasively detecting physiological ... read moreparameters. Portable instruments such as
these, have the potential to be es- sential diagnostic and health monitoring tools. The
challenges in designing a miniaturized fdNIRS instrument using sili- con integration
technology are discussed. An optimal circuit architecture for amplication, amplitude and
phase detection is proposed. Methods to reduce hardware and power consumption for a
scalable fdNIRS system are discussed. Digitization of the amplitude and phase in low
voltage CMOS processes by using peak detectors and time-to-digital converters is
implemented, which re- duces complexity while maintaining accuracy. A prototype chip
that has multiple fdNIRS sensors interfaced with exter- nal photodiodes on a 180nm CMOS
IC is implemented. The prototype chip has time coded output signals that represent the
information that needs to be measured. The optical performance as well as the amplitude
and phase digitizer response is measured. A second chip implemented in a 130nm
Silicon-Germanium BiCMOS pro- cess utilizes SiGe Bipolar transistors at the front-end
with higher gain to im- prove the sensitivity and dynamic range of the sensor. The
complete phase digitization and amplitude detection circuitry are implemented on chip
using Silicon CMOS transistors. The sensor is characterized to show sub-nW opti- cal
sensitivity, 60dB linear dynamic range and 0-360degree phase measurement on chip. These
measurements show the promise of a miniaturized solution for in-vivo non-invasive
detection of absolute concentrations of Oxy and de-Oxy-Hemoglobin in highly scattering
media.
Thesis (Ph.D.)--Tufts University, 2015.
Submitted to the Dept. of Electrical Engineering.
Advisor: Valencia Koomson.
Committee: Sergio Fantini, Sameer Sonkusale, and Shudong Jiang.
Keyword: Electrical engineering.read less - ID:
- d504rx53q
- Component ID:
- tufts:21536
- To Cite:
- TARC Citation Guide EndNote
