Movable Plunger Adjusts Optical Path Length for Nitrate Analysis
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Solution Overview
Problem
Existing light-based measurement devices for nitrate concentration in liquid samples face challenges in accurately determining concentrations across varying ranges due to the need for adjustable path lengths, which is cumbersome and prevents automated measurements.
Innovation Solution
A device with a movable plunger that adjusts path lengths by fitting different portions within the analysis cell, allowing for accurate measurements of nitrate concentration through adjustable light paths, enabling both short and long path lengths for high and low concentrations, respectively, without requiring device disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed path length is used in the analysis cell, then the device structure is simple, but accurate measurements cannot be performed for varying concentrations of nitrate
Solution Approach 1:
The plunger is made movable within the analysis cell, allowing dynamic adjustment of the path length between the light source and light detector. This enables the device to adapt to varying nitrate concentrations by selecting appropriate path lengths (shorter for high concentrations, longer for low concentrations) without requiring multiple fixed path length cells or complex disassembly procedures.
2Measurement precision
If path length is adjusted by disassembling the device, then different path lengths can be used for different concentrations, but automated measurements are prevented
Solution Approach 1:
The plunger is designed to be movable within the analysis cell, allowing automated adjustment of path length through motorized or automated mechanical actuation. This eliminates the need for manual disassembly and reassembly, enabling fully automated measurement sequences where the system can automatically select and adjust the appropriate path length based on the expected concentration range of the sample being analyzed.
Solution Approach 2:
The plunger is divided into a first portion with a first thickness corresponding to a cross-section of the analysis cell, and a second portion with a second thickness smaller than the first thickness. This segmentation allows the plunger to be positioned at different locations within the analysis cell to define different path lengths, with the second portion enabling a shorter path length measurement configuration while the first portion enables a longer path length configuration.
3Use of energy by moving object
If too low intensity light is passed through the sample, then energy consumption is reduced, but accurate determination of concentration is not possible
Solution Approach 1:
The system changes the path length parameter dynamically based on the expected concentration of nitrate in the sample. For low concentration samples, a longer path length is selected to increase light absorption and improve measurement sensitivity. For high concentration samples, a shorter path length is selected to prevent complete light absorption and maintain measurement accuracy. This parameter adjustment optimizes the balance between light energy consumption and measurement 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
Enables reliable and automated light-based measurements across a wide range of nitrate concentrations, ensuring accurate determination without the need for multiple measurements, facilitating quick and efficient analysis.
Implementation Method 1
a light source for generating light for illuminating the liquid sample in the analysis cell
Implementation Method 2
a light detector for detecting light, wherein the light detector and the light source are arranged on opposite sides of the analysis cell such that the light detector is configured to detect light having passed through the liquid sample
Implementation Method 3
Light will be absorbed by the nitrate in the sample and the measurement of transmitted light can be related to an intensity of illumination light in order to determine concentration of nitrate in the sample
Data Source
AI summary
A device for light-based analysis of a substance in a liquid sample comprises: an analysis cell for holding the liquid sample during analysis; a plunger configured for movement along walls of the analysis cell for allowing entry of the liquid sample into the analysis cell and pushing the liquid sample out of the analysis cell, wherein a first analysis measurement is allowed to be performed while a second portion of the plunger is arranged between a light source and a light detector; wherein the plunger is movable to a completely retracted position in the analysis cell for allowing a second analysis measurement to be performed such that light being detected by the light detector is passed through the liquid sample filling a space between opposite walls of the analysis cell.