Reflective Depth Interrogation for Analyte Measurement
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Solution Overview
Problem
Reflective sensing for detecting molecules in liquid samples, such as human skin, faces challenges due to signal loss and reduced precision compared to transmissive sensing, primarily because it lacks the constant volume interrogation and suffers from increased scattering and specular/diffuse reflections, which complicate accurate analyte concentration measurements.
Innovation Solution
The implementation of a reflective absorption spectroscopy process using a single radiation beam with pulsed signal and reference beams that penetrate to variable effective depths, allowing for the calculation of analyte concentration through multiple focal depths and the use of refractive index matching materials to enhance light transmission, along with temperature sensing to optimize signal capture and noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If reflective sensing is used to detect molecules in liquid samples, then non-invasive measurement capability is improved, but measurement precision deteriorates due to signal loss and scattering
Solution Approach 1:
The measurement process is segmented into multiple depth layers by varying the focal depth of the radiation beam. Multiple measurements are taken at different effective depths (e.g., 0.5mm, 1.0mm, 1.5mm) and combined through mathematical processing to reconstruct the analyte concentration, thereby overcoming the precision limitations of single-depth reflective sensing
Solution Approach 2:
A refractive index matching material is introduced as an intermediary between the radiation source and the liquid sample. This material enhances light transmission into the sample and improves the quality of reflected signals, thereby improving measurement precision without compromising the non-invasive nature of the technique
2Device complexity
If reflective sensing is used, then device complexity is reduced compared to transmissive sensing, but measurement reliability deteriorates due to increased scattering and specular/diffuse reflections
Solution Approach 1:
The system dynamically adjusts the focal depth of the radiation beam during measurement. By varying the focal depth to probe different effective depths within the sample, the system captures depth-resolved spectral information that can be processed to eliminate scattering artifacts and improve measurement reliability
Solution Approach 2:
The measurement process employs periodic pulsing of the radiation beam at different focal depths. Multiple pulses are delivered sequentially at varying depths, and the returned signals are temporally and spatially resolved to distinguish between scattering effects and true analyte absorption, thereby improving reliability
3Measurement precision
If multiple effective depths are interrogated, then measurement precision is improved through quasi-volume establishment, but measurement time increases
Solution Approach 1:
The radiation beam is pulsed periodically at different focal depths in rapid succession. Each pulse targets a specific effective depth, and the short pulse duration allows multiple depth measurements to be acquired within a brief time window, minimizing the overall measurement time while still achieving depth-resolved precision measurements
Solution Approach 2:
The focal depth of the radiation beam is dynamically adjusted between pulses to interrogate different effective depths. This dynamic focusing allows the system to rapidly switch between depth layers without mechanical movement of the entire sensing assembly, thereby reducing measurement time 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 enables accurate and reliable detection of analyte concentrations in reflective sensing, achieving precision comparable to transmissive sensing by establishing a quasi-volume for measurement and minimizing scattering noise, thus improving the accuracy and reliability of analyte concentration assessments in complex samples like human skin.
Implementation Method 1
reflective absorption spectroscopy process using a single radiation beam with pulsed signal and reference beams that are passed into a liquid sample to a variable effective depth and then reflected out of the liquid sample where it is detected and processed
Implementation Method 2
use of refractive index matching materials to enhance light transmission
Implementation Method 3
single radiation beam with two or more pulsed beams (including at least a signal beam and a reference beam) that are passed into a liquid sample
Data Source
AI summary
An absorption spectroscopy process uses a single radiation beam with two or more pulsed beams (including at least a signal beam and a reference beam) that are passed into a liquid sample to a variable effective depth and then reflected out of the liquid sample where it is detected and processed to obtain a value over a preselected time. As values are determined for multiple effective depths, a sampling dataset is obtained which is used to calculate a concentration level of a targeted particle in the liquid sample by use of calibration dataset obtained from use of known samples.