Constant Flow Physiologic Sampling Pump with Rapid Valve Switching
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Solution Overview
Problem
Existing physiologic sampling pumps struggle to rapidly follow inhalation rates and accurately collect respirable particulates due to sluggish response times and variable sampling rates, leading to inaccurate representation of inhaled doses and challenges in size-selective sampling.
Innovation Solution
A constant flow physiologic sampling pump with rapid valve switching and interchangeable sampling heads, including a cyclone or impact sampler, that maintains a constant air flow to collect gases and particulates in proportion to inhalation, using calibrated valves to minimize pump inertia and ensure accurate sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pump motor speed is varied to follow inhalation rate, then sampling proportionality is improved, but response time deteriorates due to pump inertia and air tube propagation delay
Solution Approach 1:
The system separates the flow control function from the pump motor by using a fast-responding valve to modulate a constant flow, rather than varying the pump speed directly. This segments the functions so the pump operates at constant speed while the valve provides rapid flow modulation in response to inhalation rate changes.
Solution Approach 2:
A fast-responding valve is introduced as an intermediary component between the constant flow pump and the sampling medium. The valve rapidly modulates the flow according to inhalation rate, solving the response time problem while maintaining sampling proportionality without requiring pump speed changes.
2Adaptability or versatility
If pump speed is varied to follow breathing rate, then physiologic sampling is improved, but particle collection efficiency becomes variable and unreliable
Solution Approach 1:
The system segments the flow control function from the pump operation, using a separate valve mechanism to modulate flow while the pump maintains constant speed. This ensures stable particle collection efficiency at the pump while allowing physiologic sampling through valve control.
Solution Approach 2:
Instead of changing pump speed, the system changes the flow parameters by modulating valve duty cycle. The pump operates at constant speed with stable collection efficiency, while the valve adjusts the effective sampling flow to follow breathing patterns.
3Adaptability or versatility
If long air tube is used to connect pump and collection medium, then system flexibility is improved, but flow response time deteriorates due to propagation delay
Solution Approach 1:
The fast-responding valve acts as an intermediary placed near the collection medium, allowing long air tubes to be used for system flexibility while the valve provides rapid local flow control that compensates for the propagation delay through the long tube.
Solution Approach 2:
The valve anticipates and pre-modulates the flow before changes propagate through the long air tube, compensating for the propagation delay and maintaining rapid response capability despite the long connection length.
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
The solution enables rapid and accurate sampling of airborne contaminants, providing representative air samples and overcoming previous limitations in size-selective sampling, with improved response times and accuracy compared to traditional pumps.
Implementation Method 1
the present invention is configured as a constant flow physiological sampling pump (PSP) which includes at least one valve (and when more than one valve, also includes a valve manifold) such that, in response to physiologic signal(s) from the individual being monitored
Implementation Method 2
with the further addition of varying the volume of air flowing through the collection medium in proportion to an individual's inhalation by controlling the duty cycle of an in-line valve
Data Source
AI summary
The present invention discloses a physiologic sampling pump (PSP) which uses at least one valve placed near the sampling medium to modulate air sampling to follow a person's inhalation rate and to obviate the sluggishness inherent in prior art PSPs caused by varying pump speed and by the propagation time through an air tube that connects the collection medium to prior art pumps thereby also obviating limitations inherent in system response, functionality, and accuracy. Moreover, by maintaining an essentially constant air flow through a cyclone at all times and through the collection medium while sampling, the present invention operates at known collection efficiencies, and is therefore capable of size-selective sampling of particulates as opposed to prior art PSPs that by varying the magnitude of air flow, make the separation efficiencies of pre-collection devices indeterminate and the samples worthless. When used instead with an impact sampling head, the present invention may collect total particulate as well, and may collect gases and vapors with a charcoal tube sampling head. Structural features associated with the physiological sampling pump for providing rapid response to breathing include an outer housing including a thereto-resistant case, multiple and interchangeable PSP sampling heads further including collection media and a valve(s) mounted on a valve manifold with associated tubing.