CMOS Colorimetric Sensor Array Fabrication via Random Droplet Spraying
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Solution Overview
Problem
Existing colorimetric sensors face complexity in multiplexed detection due to lens-based and lens-less optical systems, which complicate device operation and require precise alignment and masking for array formation.
Innovation Solution
A CMOS image sensor-based colorimetric sensor array is fabricated using an alignment-free and mask-free spraying method, where droplets of sensing materials are randomly distributed on the CMOS imager surface, allowing for random positioning of sensing elements, with their identity determined by comparing pre- and post-spraying images, enabling multiplexed detection of various target analytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If lens-based and lens-less optical systems are used to detect color changes in sensing materials, then detection capability is achieved, but device complexity increases and operation becomes complicated
Solution Approach 1:
The patent extracts and removes the complex optical system (lenses, mirrors, filters) from the sensor array, retaining only the essential CMOS image sensor to detect color changes. This eliminates the need for alignment and masking while maintaining detection capability through direct imaging of the sensing material array onto the CMOS sensor pixels.
Solution Approach 2:
The patent replaces the mechanical/optical alignment system with a direct digital mapping approach where the CMOS sensor directly images the sensing material array positions, eliminating mechanical complexity while preserving the ability to map sensor responses to specific sensing element locations.
2Adaptability or versatility
If multiple sensing materials are printed as an array on a support for multiplexed detection, then detection of multiple substances is enabled, but alignment and masking complexities increase
Solution Approach 1:
The patent employs self-aligned deposition techniques where sensing materials are deposited directly onto the CMOS sensor surface in predetermined patterns without requiring external alignment masks or complex positioning systems. The CMOS sensor itself serves as both the detection element and the positional reference framework.
Solution Approach 2:
The CMOS image sensor performs multiple functions: it serves as the substrate for sensing material deposition, provides the positional reference grid through its pixel array, and detects the color changes of multiple sensing materials simultaneously, eliminating the need for separate alignment and detection systems.
3Manufacturing precision
If precise alignment and masking are used for array formation, then sensing element positioning accuracy is improved, but fabrication complexity and time increase
Solution Approach 1:
The patent pre-defines the sensing element positions by programming the deposition pattern before fabrication begins, using the CMOS sensor's inherent pixel grid as the reference framework. This preliminary positioning plan eliminates the need for real-time alignment adjustments during fabrication.
Solution Approach 2:
The patent changes the fundamental parameter of positioning from mechanical alignment-based coordinates to digital pixel-coordinate mapping, where each sensing element's position is defined by its corresponding CMOS sensor pixel location, simplifying the fabrication process while maintaining precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the fabrication and operation of colorimetric sensor arrays, enabling efficient detection of multiple substances like ozone, ammonia, and nitrogen dioxide, with improved sensitivity and lifetime through the use of porous nanoparticles, and allows for random distribution of sensing elements, facilitating applications in medical diagnosis, industrial safety, and air quality control.
Implementation Method 1
droplets of a sensing fluid are sprayed directly onto a CMOS imager surface with a nozzle. The individual droplets fall onto the CMOS imager under gravity
Implementation Method 2
The sensing material interacts or reacts with a target substance (e.g., toxic chemicals or biomarkers), changing the color of the sensing material
Implementation Method 3
an optical system is used to detect light transmitted or reflected from the sensing material, and an image of the array on is formed on an image sensor
Data Source
AI summary
A colorimetric sensor array includes a CMOS image sensor having a surface including pixels and a multiplicity of colorimetric sensing elements. Each sensing element has a sensing material disposed directly on one or more of the pixels. The colorimetric sensing elements are distributed randomly on the surface of the CMOS image sensor. Fabricating the colorimetric sensor array includes spraying a sensing fluid in the form of droplets directly on a surface of a CMOS image sensor and removing the solvent from the droplets to yield a multiplicity of sensing elements on the surface of the CMOS image sensor. Each droplet covers one or more pixels of the CMOS image sensor with the sensing fluid. The sensing fluid includes a solvent and a sensing material. The droplets are distributed randomly on the surface of the CMOS image sensor.