Optical Transmission Sample Holder with Reference Light Path
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Solution Overview
Problem
Existing optical transmission measurement methods for thin samples face challenges in separating light absorption by the sample holder from that of the sample, particularly due to the presence of air bubbles and random locations, which affect the accuracy of optical density measurements.
Innovation Solution
A sample holder with a light-guiding spacer (LGS) is used to create a reference region where light transmits through the spacer without passing through the sample, allowing for the optical density of the sample to be determined by taking a ratio of light intensities between the sampling and reference regions, thereby isolating sample absorption from holder absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sample holder with two plates is used to sandwich a thin layer sample, then the sample can be held for measurement, but the light absorption by the sample holder cannot be separated from that by the sample
Solution Approach 1:
The measurement area is divided into a sample region and a reference region. The reference region contains an air bubble that provides a reference signal for the sample holder's light absorption, allowing separation of sample holder interference from sample absorption through ratio calculation.
Solution Approach 2:
An air bubble is introduced as an intermediary element in the reference region. This air bubble serves as a reference that experiences the same sample holder absorption as the sample region but without sample absorption, enabling mathematical separation of the two absorption components.
2Measurement precision
If air bubble transmission is used as reference signal, then sample holder absorption can be separated, but the reference signal becomes unreliable due to random bubble generation and location
Solution Approach 1:
The reference region is designed with specific local characteristics - a controlled air bubble of defined size and position. This local quality ensures that the reference signal is consistent and reliable, unlike random air bubbles. The reference region has differentiated properties from the sample region to provide a stable reference.
Solution Approach 2:
The air bubble is pre-positioned or pre-formed in the reference region before measurement. This preliminary action ensures that the reference signal is established and stable prior to taking measurements, eliminating the randomness and variability of spontaneously formed bubbles.
3Device complexity
If a single photodetector is used to measure both incident and transmitted light, then device complexity is reduced, but it is difficult to measure both light intensities on opposite sides of the sample
Solution Approach 1:
The incident light measurement and transmitted light measurement are merged into a single detection process. By using the reference region with the air bubble to provide a reference signal, the system can determine sample holder absorption from a single transmitted light measurement through ratio calculation, eliminating the need for separate incident light detection.
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 method improves the accuracy of optical transmission measurements by reducing errors caused by air bubbles and sample holder interference, enabling precise determination of sample properties like hemoglobin concentration.
Implementation Method 1
a light-guiding spacer (LGS) having a pillar shape, is sandwiched between the two plates with each end of the pillar in direct contact to one of the plates forming a LGS-plate contact area, and is configured to allow the light transmits from the first plate, through the LGS, to the second plate
Implementation Method 2
An optical absorption by a thin layer of a sample is one of the methods to assay a biological and chemical sample. One way to measure an optical absorption is to measure the intensity of the incident light and the transmitted light
Data Source
AI summary
Among other things, the present invention is related to devices and methods for improving optical analysis of a thin layer of a sample sandwiched between containing between two plates.