To achieve a strong color response, many colorimetric sensors rely heavily on significant physical or chemical effects such as film swelling ( 10– 12), surface wetting ( 13), particle aggregation ( 4, 14, 15), or chemical reactions ( 10, 16). These so-called “colorimetric sensors” act as transducers that translate variations in input stimuli to output color variations, fostering the delivery of qualitative and/or quantitative information without the need for laboratory-grade benchtop equipment, which is traditionally more expensive, more complex or slower to operate, and less portable.Ī primary challenge in developing colorimetric sensors is the task of achieving a meaningful color response, particularly for small variations of input stimuli (e.g., low analyte concentration, small environmental change, etc.). Along this vein, a wide variety of sensors, readable by human or artificial vision, now enables the characterization of a variety of physical and chemical attributes such as temperature ( 1), strain ( 2), humidity ( 3), pH ( 4), heat transfer ( 5), and presence or concentration of target analytes (e.g., chemicals, biomarkers) ( 6– 9). Similarly, the emergence of pervasive artificial imaging systems based on low-cost, portable, and high-resolution digital color cameras offers the potential to exploit luminance, chromaticity, temporal, and spatial degrees of freedom to support the on-demand analysis of sensors responding to specific input stimuli.
#Color finesse le vs pi portable
The human color vision system is a highly evolved means for spatiotemporally resolving chromaticity and luminance characteristics of illuminated objects, making it one of the most powerful and inherently portable diagnostic tools in history. 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. 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/mm 2, lower than industry standard sensors based on surface plasmon resonance that require spectral or angular interrogation. 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.
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. Our approach combines structural color optical filters as sensing elements alongside a multichromatic laser illuminant. In this work, we demonstrate a general colorimetric sensing technique that overcomes the performance limitations of existing chromatic and luminance-based sensing techniques. 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.
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.
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