Ratiometric, filter-free optical sensor based on a complementary metal oxide semiconductor buried double junction...

Area of Science:

• Materials Science
• Electrical Engineering
• Analytical Chemistry

Background:

• Traditional chemical sensing often requires complex optical setups, including filters and monochromators.
• Rayleigh scatter can interfere with accurate intensity measurements in optical sensing.
• Sensor signal drift and source intensity fluctuations can lead to measurement errors.

Purpose of the Study:

• To develop a novel complementary metal oxide semiconductor integrated circuit (CMOS IC) with a buried double junction (BDJ) photodiode.
• To demonstrate a real-time sensing platform that eliminates the need for optical filters.
• To validate the BDJ platform's performance for gaseous NH3 and aqueous pH detection.

Main Methods:

• Fabrication of a CMOS IC incorporating a BDJ photodiode.
• Real-time signal acquisition related to intensity ratios at two emission wavelengths.
• Comparative analysis of BDJ platform performance against a slew scanned fluorimeter (SSF).

Main Results:

• The BDJ photodiode provides a real-time output signal proportional to intensity ratios at two wavelengths.
• The BDJ platform effectively eliminates the need for optical filters to block Rayleigh scatter.
• BDJ performance was functionally equivalent to SSF, without wavelength filtering or monochromators.
• The BDJ platform demonstrated robustness against source intensity fluctuations and sensor signal drift.

Conclusions:

• The developed BDJ photodiode integrated circuit offers a filter-less, real-time sensing solution.
• This technology provides accurate and reliable measurements for gaseous NH3 and aqueous pH.
• The BDJ platform presents a significant advancement over traditional fluorimetry, enhancing accuracy and simplifying instrumentation.