UV-Sensing Sheet with Microencapsulated Leuco Dyes for Wide-Range Irradiance Measurement
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Solution Overview
Problem
Existing ultraviolet dosimeters, including semiconductor photovoltaic devices and photochromic cards, are either expensive, not portable, or lack sensitivity and accuracy in measuring cumulative ultraviolet irradiance, particularly in the range of 100 to 1,000 mJ/cm2, which is crucial for manufacturing processes involving UV curing.
Innovation Solution
An ultraviolet-sensing sheet with a specific change in reflection density at various cumulative illuminance ranges, incorporating a photo-oxidant and leuco dye in a microcapsule formulation, allowing continuous color development and precise measurement of UV irradiance from 1 to 1,000 mJ/cm2, using a high-pressure mercury lamp at 365 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photochromic cards are used for ultraviolet measurement, then the cost is reduced and portability is improved, but the measurement precision of cumulative illuminance is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the sensing material by using a specific leuco dye composition (leuco crystal violet, leuco malachite green, and leuco methylene blue in a mass ratio of 1:(0.1-0.5):(0.1-0.5)) and controlling the photo-oxidant to leuco dye mass ratio (0.01-0.1:1). This parameter optimization enables the material to exhibit continuous color development across a wide cumulative illuminance range (1-1000 mJ/cm2), thereby improving measurement precision while maintaining the low-cost advantage of chemical dosimeters.
Solution Approach 2:
The patent creates a composite sensing material by combining multiple leuco dyes (leuco crystal violet, leuco malachite green, and leuco methylene blue) with a photo-oxidant in a specific formulation. This composite structure allows the material to respond to a broad spectrum of ultraviolet radiation and provides continuous color development across different illuminance levels, significantly improving cumulative illuminance measurement precision compared to single-component photochromic materials.
2Measurement precision
If photosensitive paper methods are used, then ultraviolet dose can be determined, but the procedure becomes complicated and external light susceptibility increases
Solution Approach 1:
The patent employs a self-developing chemical system where the leuco dye composition automatically undergoes photo-oxidation upon ultraviolet exposure, producing a permanent color change that directly indicates the cumulative illuminance. The microcapsule formulation contains all necessary components (leuco dyes, photo-oxidant, and encapsulating agents) that self-assemble and self-react upon UV exposure, eliminating the need for external developers, fixers, or complex processing equipment. The result is a simplified single-step measurement procedure that reduces operational complexity while maintaining accurate ultraviolet dose determination.
3Measurement precision
If oxidative coloration of leuco dyes is used, then ultraviolet dose can be measured, but image stability decreases and external light susceptibility increases
Solution Approach 1:
The patent applies microencapsulation technology to protect the leuco dye and photo-oxidant components from premature reaction and environmental degradation. The microcapsule wall acts as a protective barrier that isolates the sensitive chemical components until ultraviolet exposure triggers the intended photo-oxidation reaction. This beforehand protection prevents unwanted interactions with external light and maintains image stability, while still allowing accurate ultraviolet dose measurement through the controlled color development process.
Solution Approach 2:
The microcapsule structure serves as an intermediary between the leuco dye composition and the external environment. It selectively allows ultraviolet radiation to penetrate and trigger the photo-oxidation reaction while blocking harmful external light and preventing premature reaction. This intermediary protection mechanism maintains the stability of the sensing material during storage and handling, ensuring that image quality remains stable until the measurement is actually performed.
4Reliability
If conventional dosimeters are used for UV curing measurement, then measurement capability is provided, but sensitivity in the range of 100 to 1,000 mJ/cm2 is insufficient
Solution Approach 1:
The patent optimizes the chemical composition parameters of the leuco dye system by using a specific tri-color leuco dye formulation (leuco crystal violet, leuco malachite green, and leuco methylene blue) with controlled mass ratios. This parameter optimization extends the linear response range of the dosimeter to cover the critical UV curing range of 100-1000 mJ/cm2, providing enhanced sensitivity and measurement precision specifically for industrial UV curing applications where conventional dosimeters fail to provide adequate resolution.
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
The sheet provides sensitive and accurate detection of UV irradiance over a wide area, enabling effective measurement of UV doses in the specified range, improving handling and image stability, and reducing external light susceptibility.
Implementation Method 1
an ultraviolet-sensing sheet which has a change in reflection density ΔD1 of 0.2 or more over a range of cumulative illuminance 1 mJ/cm2 or more and less than 10 mJ/cm2, a change in reflection density ΔD2 of 0.2 or more over a range of cumulative illuminance 10 mJ/cm2 or more and less than 100 mJ/cm2, and a change in reflection density ΔD3 of 0.2 or more over a range of cumulative illuminance 100 mJ/cm2 or more and 1,000 mJ/cm2 or less, as measured at a wavelength of 365 nm when the ultraviolet-sensing sheet is irradiated with a high-pressure mercury lamp
Data Source
AI summary
Provided an ultraviolet-sensing sheet that facilitates measurement of ultraviolet irradiance over a wide area, that is suitable in ultraviolet irradiance in a range from 1 to 1,000 mJ/cm2, a method for manufacturing such an ultraviolet-sensing sheet, and a method for sensing ultraviolet. The ultraviolet-sensing sheet has a change in reflection density ΔD1 of 0.2 or more over a range of cumulative illuminance 1 mJ/cm2 or more and less than 10 mJ/cm2,a change in reflection density ΔD2 of 0.2 or more over a range of cumulative illuminance 10 mJ/cm2 or more and less than 100 mJ/cm2, and a change in reflection density ΔD3 of 0.2 or more over a range of cumulative illuminance 100 mJ/cm2 or more and 1,000 mJ/cm2 or less,as measured at a wavelength of 365 nm when the ultraviolet-sensing sheet is irradiated with a high-pressure mercury lamp.