Stop-Start Microfluidic Calorimetry with NHA Sensors
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Solution Overview
Problem
Conventional calorimetry methods using optical-based temperature sensing struggle with sensitivity in detecting small temperature changes and are affected by air bubbles in microfluidic channels, which disrupt measurements and lead to unreliable data acquisition.
Innovation Solution
The Stop-Start method involves measuring baseline and reaction extraordinary optical transmission (EOT) through Nano Hole Array sensors in a co-flow reactor microchannel, where the flow of fluids is controlled to prevent bubble formation by stopping and emptying the channel before mixing, allowing for accurate calorimetry measurements without additional devices or fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical-based temperature sensing is used in microfluidic channels, then temperature changes can be detected, but air bubbles form and disrupt measurements reducing reliability
Solution Approach 1:
The system performs preliminary actions by pre-flushing microfluidic channels with carrier fluid before introducing reactants, and by implementing a stop-start flow method that empties channels between measurements. This prevents air bubble formation at the source and ensures channels are filled with fluid before each measurement, thereby maintaining measurement reliability while preserving optical detection capability.
Solution Approach 2:
The system employs periodic stop-start flow cycles where fluid flow is interrupted, channels are emptied, and then refilled before each measurement. This periodic action removes air bubbles that would otherwise accumulate and disrupt optical measurements, ensuring reliable data acquisition while maintaining the ability to detect temperature changes through EOT measurements.
2Productivity
If continuous flow is maintained in microfluidic channels, then measurement time is reduced, but air bubbles accumulate and disrupt optical measurements
Solution Approach 1:
The system implements periodic stop-start flow cycles that interrupt continuous flow to empty channels of accumulated air bubbles. This periodic interruption removes the harmful accumulation effect while maintaining overall productivity by quickly refilling channels and resuming flow for the next measurement cycle.
Solution Approach 2:
The system maintains continuity of useful action by rapidly refilling channels with carrier fluid or reactant mixtures after each stop period. The useful action of having fluid-filled channels for measurement is restored immediately after bubble removal, minimizing downtime and maintaining high measurement throughput while ensuring data quality.
3Productivity
If reactants are mixed continuously in flowing streams, then reaction occurs efficiently, but air bubbles form at interfaces and affect measurements
Solution Approach 1:
The system performs preliminary flushing of channels with carrier fluid before introducing reactant mixtures. This preliminary action ensures channels are completely filled with liquid, eliminating air pockets that would form at fluid interfaces during subsequent reactant mixing and flow, thereby preventing bubble-related measurement disruptions while maintaining efficient reaction conditions.
Solution Approach 2:
The system uses carrier fluid as an intermediary substance that fills microfluidic channels before and during reactant introduction. This intermediary fluid displaces air from the channel, creating a bubble-free environment that allows efficient reactant mixing and flow without the harmful effect of air bubbles forming at fluid interfaces.
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
This approach eliminates the disruptive effect of air bubbles, enabling repeatable and ultra-sensitive calorimetry data acquisition, reducing experimental time, and providing reliable thermodynamic property measurements.
Implementation Method 1
transmission of light is measured through a Nano Hole Array (NHA) sensor to obtain a baseline extraordinary optical transmission (EOT) measurement
Implementation Method 2
flowing the first fluid and a second fluid through the co-flow reactor microchannel such that a reaction occurs at least at a diffusion interface of the fluids
Data Source
AI summary
A method for calorimetry includes flowing a first fluid through a co-flow reactor microchannel having plural inlets and an outlet, the first fluid flowing through each of the inlets, and measuring transmission of light through a Nano Hole Array (NHA) sensor to obtain a baseline extraordinary optical transmission (EOT) measurement. The flow of the first fluid is stopped, the microchannel is emptied of the first fluid, and the first fluid and a second fluid are passed through the microchannel such that a reaction occurs, the first fluid flowing through a first of the inlets and the second fluid flowing through a second of the inlets. While flowing the first and second fluids, transmission of light through the NHA sensor is measured to obtain a reaction EOT measurement. A calorimetry measurement, indicative of energy released during the reaction, is calculated as a function of the baseline and reaction EOT measurements.