CMOS Tunable-Wavelength Multi-Color Photogate Sensor

Abstract

A CMOS tunable-wavelength multi-color photogate (CPG) sensor is presented. Sensing of a small set of well-separated wavelengths (e.g., > 50 nm apart) is achieved by tuning the spectral response of the device with a bias voltage. The CPG employs the polysilicon gate as an optical filter, which eliminates the need for an external color filter. A prototype has been fabricated in a standard 0.35 μm digital CMOS technology and demonstrates intensity measurements of blue (450 nm), green (520 nm), and red (620 nm) illumination with peak signal-to-noise ratios (SNRs) of 34.7 dB , 29.2 dB, and 34.8 dB, respectively. The prototype is applied to fluorescence detection of green-emitting quantum dots (gQDs) and red-emitting quantum dots (rQDs). It spectrally differentiates among multiple emission bands, effectively implementing on-chip emission filtering. The prototype demonstrates single-color measurements of gQD and rQD concentrations to a detection limit of 24 nM, and multi-color measurements of solutions containing both colors of QDs to a detection limit of 90 nM and 120 nM of gQD and rQD, respectively.

Improvement of dynamic range of filter-less fluorescence sensor with body-biasing technique

“…An alternative is to use previously designed fluorescence labels. In addition, fluorescence sensors using deeply buried p-n junction photodiodes have been developed, [14][15][16][17][18] and color information can be inferred by sensing at several depths. Although the buried junction approach achieves a high spatial density and is suitable for photographic applications requiring only three colors, the number of diodes that can be implemented is limited.…”

CMOS Time-Resolved, Contact, and Multispectral Fluorescence Imaging for DNA Molecular Diagnostics

“…In [ 2 , 5 ], a CMOS multispectral sensor is proposed to detect and differentiate the multi-color emission, eliminating the need to mechanically swap optical filters. As a result, the complexity of the microsystem is significantly reduced by the integration of the CMOS sensor.…”

“…Deoxyribonucleic acid (DNA) analysis platforms are used in the life sciences for the observation, identification, and characterization of various biological systems. These platforms serve applications such as pathogen detection [ 1 , 2 ], disease screening [ 3 , 4 ], biohazard detection [ 5 , 6 ], cancer diagnostics [ 7 , 8 ], and genetic research [ 9 – 11 ]. Biosensors are a subset of such platforms that can convey biological parameters in terms of electrical signals.…”

“…Well-known molecular sensing techniques include electrochemical detection [ 3 , 13 ], surface plasmon resonance [ 14 ], and fluorescence [ 2 , 4 , 5 ]. In electrochemical DNA detection, for example, a charge-transfer chemical reaction causes a change in the electrical properties of the system.…”

“…A quantitative measure of the degree of hybridization, reflecting the target concentration, is obtained by monitoring the reduction-oxidation current. Although electrochemical techniques are capable of highly spatially multiplexed detection and often leads to simple electronic readout, it is generally more difficult to achieve combined high selectivity and high sensitivity as compared to an assay using well-chosen optical labels to interrogate specific processes [ 3 , 5 , 13 ].…”