Sorbent Recess Locking for Sampling Probe Durability
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Solution Overview
Problem
Conventional sorbent sampling probes, such as those using Polydimethylsiloxane (PDMS), face limitations in capacity due to the need to fit within a needle, leading to damage from frictional engagement with septa seals and frequent replacement, compromising sample integrity.
Innovation Solution
A sampling probe design featuring an elongate body with a recessed sorbent element that is mechanically locked within the body, preventing relative movement and exposure to septa contact, allowing for increased sorbent volume and reduced wear, with a sleeve configuration that includes enlarged diameter sections to securely house the sorbent material and prevent liquid ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the sorbent layer is made thick to increase sampling capacity, then the sampling capacity is improved, but the probe becomes susceptible to wear and damage from frictional engagement with septa seals
Solution Approach 1:
The sorbent element is nested within a recess in the probe body, with the sorbent material housed inside a protective cavity rather than exposed on the outer surface. This nesting arrangement allows thick sorbent layers to be incorporated while protecting the sorbent material from frictional damage during septa engagement.
Solution Approach 2:
The sorbent material is extracted from the outer surface of the probe and relocated to an internal recess. This separation removes the vulnerable sorbent layer from direct contact with septa seals, eliminating the wear problem while preserving sampling capacity.
2Reliability
If the sorbent element is secured using chemical bonding, then the sorbent element can be secured to the body, but chemical bonding is difficult to achieve and may not prevent dragging by septa
Solution Approach 1:
Chemical bonding is replaced with a mechanical locking system where the sorbent element is physically retained within a recess by geometric constraints. The recess geometry provides mechanical interlocking that secures the sorbent element without relying on difficult-to-achieve chemical bonds.
Solution Approach 2:
The probe structure is segmented into distinct components: the body, the recess, and the sorbent element. This segmentation allows the sorbent element to be independently secured within the recess using mechanical features such as interference fits or retention structures.
3Ease of operation
If the sorbent material is exposed on the outer surface for easy access, then the sorbent material can be easily contacted, but the sorbent material is susceptible to damage and removal from the surface
Solution Approach 1:
The sorbent element is nested within an internal recess of the probe body, protecting it from external damage while maintaining functionality. The recess acts as a protective cavity that shields the sorbent material from frictional engagement with septa seals.
Solution Approach 2:
The sorbent material is extracted from the vulnerable outer surface and relocated to a protected internal position within the recess, eliminating exposure to harmful frictional forces while preserving the sorbent's analytical function.
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
Enhances sampling capacity and reduces sorbent material wear, ensuring consistent sample integrity and extended probe lifespan by securely housing the sorbent material within the probe body, preventing damage during use.
Implementation Method 1
PDMS extraction is based on adsorption, an equilibrium technique based on the partitioning of analytes between the silicone and the aqueous phases. The sorptive material is placed into a liquid sample, and the sorptive material absorbs the compound of interest contained therein.
Implementation Method 2
PDMS extraction is based on adsorption, an equilibrium technique based on the partitioning of analytes between the silicone and the aqueous phases. The extraction into the PDMS can be estimated based on the octanol-water partition coefficient of the analyte (K O/W).
Data Source
AI summary
A sample probe for sorptive sampling comprises an elongate body having a longitudinal axis defined along its length and a radial axis extending transverse to the longitudinal axis. A sorbent element formed of a sorbent material is secured to the body. The elongate body has an outer surface and a recess located along the length of the body that extends radially into the outer surface. The sorbent element is at least partially received within the recess of the body which mechanically locks the sorbent element to the body to prevent relative longitudinal movement of the sorbent element relative to the body.