Nanomembrane Flow Sensor via Microwave Resonator
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Solution Overview
Problem
Current flow rate sensors for microfluidics are inadequate for on-chip applications, leading to inaccuracies and complications in biomedical research and ventilation machines, particularly during the COVID-19 pandemic, due to their external placement and inability to provide fine and coarse flow rate measurements effectively.
Innovation Solution
A flow rate sensor mechanism utilizing a microwave resonator that converts fluid flow-induced instability on a nanomembrane into a sensing mechanism, where the resonance frequency changes are measured to determine flow rates, enabling precise and on-chip flow rate monitoring with sensitivity to 0.1 μL/min increments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercial flow sensors are used outside the chip, then flow rate measurements can be performed, but the measurements are inaccurate and the system complexity increases
Solution Approach 1:
The patent merges the flow sensing function directly into the microfluidic chip by integrating a nanomembrane sensor structure within the chip architecture. The nanomembrane is positioned to interact with fluid flow inside the microchannel, and its deflection is detected by integrated readout mechanisms, eliminating the need for external flow sensors and achieving both on-chip integration and accurate flow rate measurements
Solution Approach 2:
The patent introduces a nanomembrane as an intermediary element that converts fluid flow parameters into measurable mechanical deflection. The nanomembrane acts as a mediator between the fluid flow and the detection system, translating flow rate information into membrane displacement that can be read out by integrated sensors, thereby enabling accurate on-chip flow measurement
2Reliability
If external flow sensors are used, then flow rate control is possible, but delay and fluctuations affect the studies negatively
Solution Approach 1:
The patent implements preliminary action by pre-positioning the nanomembrane sensor within the microfluidic channel to continuously monitor flow conditions. The sensor is prepared and integrated in advance, enabling immediate detection of flow rate changes without the delays associated with external sensors, thus improving response time and control stability
Solution Approach 2:
By merging the flow sensing function into the chip structure itself, the patent eliminates the temporal delays and fluctuations introduced by external sensors. The integrated nanomembrane sensor responds immediately to flow changes within the microchannel, providing real-time feedback that enhances reliability and reduces response time
3Measurement precision
If perforated cantilever structures are used for flow sensing, then flow rate measurement at nL/min level is accomplished, but the fabrication becomes complicated
Solution Approach 1:
The patent employs a thin nanomembrane structure instead of complex perforated cantilever assemblies. The nanomembrane is a simple, continuous thin film that deflects in response to flow pressure, achieving high measurement sensitivity at nL/min levels while being much easier to fabricate using standard thin-film deposition and release techniques, thereby simplifying the manufacturing process
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 provides accurate and sensitive flow rate measurements, enabling effective on-chip monitoring and control of microfluidic components, and is suitable for ventilation machines, addressing the limitations of existing sensors by integrating the sensing mechanism directly on the chip.
Implementation Method 1
a constant flow rate can induce instability on a mechanical element, an effect that can readily be observed in the fluttering of flags and papers
Implementation Method 2
the resonance frequency of which is influenced, preferably capacitively by the deflection of the nanomembrane
Data Source
AI summary
The present invention relates to a device wherein fluid or air-induced instability is converted into a flow sensing mechanism by building a CPW (Coplanar Wave Guide) resonator. Depending on the flow rate, periodic transitions between two bistable states emerge. Owing to the dependence of the transition period and the flow rate, the use of this effect for on-chip flow rate sensing is achieved with this invention. Moreover, the present invention ensures a flow rate sensor to be used in the ventilation machines for the treatment of the COVID-19 pandemic.