A smartphone biosensor based on analysing structural colour of porous silicon

Cao, Tian; Zhao, Yiliang; Nattoo, Crystal A.; Layouni, Rabeb; Weiss, Sharon M.

doi:10.1039/c9an00022d

Cited by 21 publications

(15 citation statements)

References 29 publications

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“…These values are competitive with or lower than the LOD, ∼10 pg mm −2 , of conventional surface plasmon resonance techniques (35,36), which require spectral or angular interrogation, yet our sensor achieves label-free color changes that are detectable directly by the naked eye. As summarized in Table 1, our HSC scheme enabled demonstration of an enhanced colorimetric sensitivity ∂E 00 =∂λ, which is ∼7 to 30 times higher than recently reported structural colorbased sensors (6,7,37). Combined with the use of a highsensitivity porous medium, our structure enhances both terms of Eq.…”

Section: Resultsmentioning

confidence: 85%

“…Narrowband illumination of structural color sensors, as shown in Fig. 1B, has previously been demonstrated as a means for achieving high sensitivities and reducing the LOD by providing amplified luminance variations in response to small spectral perturbations (6,7). As viewed from CIE xyY color space, monochromatic sensors are restricted to one-dimensional color changes along the luminance coordinate Y, where variations in chromaticity are strictly 0: Δx = Δy = 0.…”

Section: Approach/frameworkmentioning

confidence: 99%

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Hyperchromatic structural color for perceptually enhanced sensing by the naked eye

Talukdar

McCoy

Timmins

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Colorimetric sensors offer the prospect for on-demand sensing diagnostics in simple and low-cost form factors, enabling rapid spatiotemporal inspection by digital cameras or the naked eye. However, realizing strong dynamic color variations in response to small changes in sample properties has remained a considerable challenge, which is often pursued through the use of highly responsive materials under broadband illumination. In this work, we demonstrate a general colorimetric sensing technique that overcomes the performance limitations of existing chromatic and luminance-based sensing techniques. Our approach combines structural color optical filters as sensing elements alongside a multichromatic laser illuminant. We experimentally demonstrate our approach in the context of label-free biosensing and achieve ultrasensitive and perceptually enhanced chromatic color changes in response to refractive index changes and small molecule surface attachment. Using structurally enabled chromaticity variations, the human eye is able to resolve ∼0.1-nm spectral shifts with low-quality factor (e.g., Q ∼ 15) structural filters. This enables spatially resolved biosensing in large area (approximately centimeters squared) lithography-free sensing films with a naked eye limit of detection of ∼3 pg/mm2, lower than industry standard sensors based on surface plasmon resonance that require spectral or angular interrogation. This work highlights the key roles played by both the choice of illuminant and design of structural color filter, and it offers a promising pathway for colorimetric devices to meet the strong demand for high-performance, rapid, and portable (or point-of-care) diagnostic sensors in applications spanning from biomedicine to environmental/structural monitoring.

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Section: Resultsmentioning

confidence: 85%

Section: Approach/frameworkmentioning

confidence: 99%

Hyperchromatic structural color for perceptually enhanced sensing by the naked eye

Talukdar

McCoy

Timmins

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…A porous silicon microcavity (PSM) is an FPI structure created by two DBRs with a thin layer of porous silicon (PS). PS is inexpensive, easy to fabricate, and has a large sensing surface, so it has been widely investigated to develop label-free optical biosensors [ 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 ]. The refractive index of a PS layer is determined by the porosity, which can be modulated by adjusting parameters of electrochemical etching such as the etching time and current density.…”

Section: Fabry-perot Interferometer (Fpi)-based Biosensorsmentioning

confidence: 99%

“…Some researchers investigated the potential of PSM-based biosensors for multiplexed, real-time detection, and POC diagnostics [ 56 , 59 , 60 ]. Pham et al presented a PSM sensor to detect two different organic solvents simultaneously and measure the low concentration of pesticides in water [ 59 ].…”

Section: Fabry-perot Interferometer (Fpi)-based Biosensorsmentioning

confidence: 99%

“…The refractive index sensing was done by measuring different concentrations of ethanol in DI water with an LOD of 1000 nm/RIU, corresponding to 10 −7 RIU. Recently, Cao et al reported a smartphone-based PSM-biosensor for POC diagnostics [ 60 ]. The built-in LED with a band-pass filter (BPF) and the camera of a smartphone were used as a light source and a detector of the platform, respectively, as shown in Figure 9 c. A shift in the reflectance spectrum from the adsorption of target molecules on the PSM was detected as an intensity change measured by a smartphone camera.…”

Section: Fabry-perot Interferometer (Fpi)-based Biosensorsmentioning

confidence: 99%

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Label-Free Optical Resonator-Based Biosensors

Rho

Breaux

Kim

2020

Sensors

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The demand for biosensor technology has grown drastically over the last few decades, mainly in disease diagnosis, drug development, and environmental health and safety. Optical resonator-based biosensors have been widely exploited to achieve highly sensitive, rapid, and label-free detection of biological analytes. The advancements in microfluidic and micro/nanofabrication technologies allow them to be miniaturized and simultaneously detect various analytes in a small sample volume. By virtue of these advantages and advancements, the optical resonator-based biosensor is considered a promising platform not only for general medical diagnostics but also for point-of-care applications. This review aims to provide an overview of recent progresses in label-free optical resonator-based biosensors published mostly over the last 5 years. We categorized them into Fabry-Perot interferometer-based and whispering gallery mode-based biosensors. The principles behind each biosensor are concisely introduced, and recent progresses in configurations, materials, test setup, and light confinement methods are described. Finally, the current challenges and future research topics of the optical resonator-based biosensor are discussed.

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Functionalization of Oxide‐Free Silicon Surfaces for Biosensing Applications

Henriksson

Neubauer

Birkholz

2021

Adv Materials Inter

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As an alternative to standard silicon biofunctionalization protocol based on alkoxysilanes that bind to SiO2 on oxidized silicon substrates, several protocols to form bifunctional interlayers that directly bind to the silicon surface via a strong SiC bond have been developed during the last decades. These interlayers are more stable, and the lack of an insulating layer between the substrate and the interlayer reduces electric noise in biosensor devices. SiC monolayers are not yet regularly applied as the protocols are more complex and generally require an inert gas atmosphere. However, a variety of applications and new methods to form bifunctional SiC interlayers are recently developed. Here, the role these innovative protocols and interlayers play in biofunctionalization of silicon surfaces is reviewed and their applications in electrochemical, microelectromechanical, and optical biosensing are reported. From the analysis of the current situation, it can be concluded that the advantageous properties offered with this approach in many cases more than outweigh the additional processes to form SiC bonded interlayers and the approach is predicted to expand the applications of future silicon‐based biosensors.

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A smartphone biosensor based on analysing structural colour of porous silicon

Abstract: A smartphone biosensor with minimal external components is demonstrated for highly sensitive detection of biomolecules by monitoring the structural colour of a porous silicon film.

Cited by 21 publications

References 29 publications

Hyperchromatic structural color for perceptually enhanced sensing by the naked eye

Hyperchromatic structural color for perceptually enhanced sensing by the naked eye

Label-Free Optical Resonator-Based Biosensors

Functionalization of Oxide‐Free Silicon Surfaces for Biosensing Applications

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