Capillary Blood Sampling Device for Painless Mid-IR Spectroscopy
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Solution Overview
Problem
Conventional methods for collecting bodily fluids, such as blood, are painful, inefficient, and prone to complications due to the need for large sample volumes and manual, invasive procedures, which hinder effective chemical analysis.
Innovation Solution
A sample holder using a capillary force to draw small volumes of fluid without causing pain, featuring a stainless-steel hypodermic needle and a float-zone silicon chamber transmissive to mid-infrared radiation for spectroscopic analysis, allowing for efficient and painless collection and analysis of bodily fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional large-volume blood drawing methods are used, then sufficient sample volume for testing is obtained, but patient pain and distress increase significantly
Solution Approach 1:
The patent changes the key parameter of sample volume from conventional large volumes (several milliliters) to micro-volumes (nanoliters to microliters). This parameter change enables sufficient chemical analysis with dramatically reduced patient pain and distress, as the micro-needle causes minimal tissue damage and the brief contact time reduces suffering
2Reliability
If manual blood drawing procedures are used, then trained personnel can obtain blood samples, but the process is time-consuming and prone to errors
Solution Approach 1:
The micro-needle device enables self-service blood collection where patients can obtain their own blood samples without trained personnel. The device automatically draws blood through capillary action and delivers it to the analysis chip, eliminating the need for manual vein selection, needle insertion, and sample transfer, thereby reducing both time and error potential
Solution Approach 2:
The patent replaces the manual mechanical blood drawing process with an automated microfluidic system. Capillary forces and pressure differentials automatically draw blood through the micro-needle and transport it to the analysis chamber, eliminating manual manipulation and reducing procedural time and errors
3Reliability
If lancelet-based blood drawing is used, then in-vivo puncture complications are avoided, but only small amounts of blood are obtained before clotting
Solution Approach 1:
The patent replaces the mechanical puncture-and-collect method with a micro-needle insertion followed by automated microfluidic transport. The micro-needle creates a minimal puncture that draws blood continuously through capillary action and applied pressure, delivering sufficient volume (several microliters) to the sealed analysis chamber before clotting can occur, whereas lancelets rely on passive collection that allows clotting to limit volume
4Measurement precision
If conventional spectroscopic analysis is used, then chemical composition can be determined, but large sample volumes are required
Solution Approach 1:
The patent transitions from bulk liquid sample analysis to thin-film or interfacial analysis. The micro-needle delivers blood as a thin layer or droplet on the functionalized chip surface, and spectroscopic methods (such as surface-enhanced Raman scattering or attenuated total reflectance) analyze the chemical composition of this minimized sample volume with high precision, enabling accurate measurement with nanoliter to microliter quantities
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 painless and efficient analysis of small-volume test samples, reducing patient discomfort and the need for large blood draws, while preventing bubble formation and enhancing capillary drawing capabilities.
Implementation Method 1
a capillary channel that fluidically couples the inlet port and the sample region, wherein the capillary channel is dimensioned and arranged to induce a capillary force operative for drawing the liquid from the inlet port into the sample region
Data Source
AI summary
A sample holder that enables mid-infrared spectroscopy of a test sample using mid-infrared light is disclosed. The sample holder includes an inlet port and a sample chamber that comprises a sample region and a capillary channel that fluidically couples the inlet port and the sample region. The capillary channel is characterized by a higher capillary force than the sample region. As a result, when the inlet port is put in contact with a liquid containing the test sample, the liquid is drawn into the sample region without the formation of bubbles that could obscure the optical analysis. In some embodiments, the inlet port is the free end of a draw tube having an outer diameter that is smaller than the minimum spacing between pain receptors at a draw site on a patient, which mitigates pain felt by the patient due to insertion of the draw tube at the draw site.