Colorimetric porous photonic bandgap sensors with integrated CMOS color detectors

We developed a low-detection-limit filter-free fluorescence sensor by a charge accumulation technique. For charge accumulation, a floating diffusion amplifier (FDA), which included a floating diffusion capacitor, a transfer gate, and a source follower circuit, was used. To integrate CMOS circuits with the filter-free fluorescence sensor, we adopted a triple-well process to isolate transistors from the sensor on a single chip. We detected 0.1 nW fluorescence under the illumination of excitation light by 1.5 ms accumulation, which was one order of magnitude greater than that of a previous current detection sensor.

Section: Introductionmentioning

confidence: 99%

Improvements of low-detection-limit filter-free fluorescence sensor developed by charge accumulation operation

Tanaka¹,

Choi²,

Moriwaki³

et al. 2017

“…[7][8][9][10][11][12][13][14] Recently, the integration of a fluorescence sensor on optical filters to develop a miniaturized sensor has been studied. [15][16][17] This sensor can be integrated into a circuit, although the fabrication in process is complex. In order to solve this problem, a fluorescence sensor coating an optical filter was developed.…”

Section: Introductionmentioning

confidence: 99%

Filter-less fluorescence sensor with high separation ability achieved by the suppression of forward-scattered light in silicon

Choi¹,

Takahashi²,

Matsuda³

et al. 2016

The improvement of a filter-less fluorescence sensor, by suppressing forward scattering in silicon by surface planarization is presented. A fluorescence microscope has been widely used in biochemical fields. However, it is difficult to miniaturize because optical filters and other parts are necessary. We previously developed a filter-less fluorescence sensor. The separation ability of excitation light and fluorescence in the previous device was 550:1. It is necessary to improve the separation ability. This study focuses on the suppression of forward-scattered incident light in silicon, through the enhanced surface planarization of polysilicon, which is the gate electrode material. The separation ability of the filter-less fluorescence sensor was increased from 550:1 to 1250:1 by the suppression of forward-scattered light.

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Moriwaki

Takahashi

Akita

et al. 2015

Although fluorescence microscopy is an important technique in biomedical fields, the bulky equipment is disadvantageous in some situations. We have previously proposed a filter-less fluorescence sensor whose operation is based on the light absorption coefficient, which depends on the wavelength in a silicon substrate. In this sensor, the ratio of the excitation light intensity to the fluorescence intensity is as high as 400 : 1 upon optimizing the impurity concentration and the depth of the p-well region. To improve the dynamic range, herein we use a body-biasing technique to optimize the potential distribution of the sensing area to acquire sufficient photocurrent. Consequently, the dynamic range of the filter-less fluorescence sensor is improved to 800 : 1 with an 8 V substrate voltage.