Micro-machined Thermal Time-of-Flight Sensor for Fluidic Metrology
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Solution Overview
Problem
Current fluid measurement technologies face challenges in accuracy, reliability, and cost due to limitations in mechanical approaches, slow response times in electrochemical sensing, and non-monotonic dynamic ranges, particularly in measuring fluidic flow rate, concentration, and density, especially in applications like drug infusion and fuel cell efficiency.
Innovation Solution
A micro-machined thermal time-of-flight sensor integrated with a thermal diffusivity sensor in a closed conduit configuration allows simultaneous measurement of fluidic flow rate and concentration, using dual-sensing chips with thermal sensing principles and a microheater, enabling accurate and reliable metrology data across a wide dynamic range without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal calorimetry is used to measure fluidic flow rate, then flow rate measurement is achieved, but constant heating causes instability for long term reliability
Solution Approach 1:
The patent uses periodic heating instead of constant heating, where the heater is activated in pulses or cycles. This periodic thermal excitation allows measurement of flow rate through thermal response while avoiding the instability caused by continuous heating, thereby maintaining measurement precision while improving long term reliability
Solution Approach 2:
The patent changes the heating parameter from constant to variable/periodic, and adjusts the measurement approach to use thermal response characteristics rather than steady-state temperature. This parameter change enables accurate flow rate measurement without the reliability issues of constant heating
2Device complexity
If electrochemical sensing is used to measure liquid concentration, then structure is simple, but response time is very slow
Solution Approach 1:
The patent replaces electrochemical sensing with thermal sensing methodology. Instead of using electrochemical reactions that are slow, the patent uses thermal diffusion and convection measurements that provide rapid response while maintaining simple device structure through integrated thermal sensors
Solution Approach 2:
The patent utilizes thermal phase transitions or thermal wave propagation through the fluid to achieve rapid concentration measurement. The thermal response time is much faster than electrochemical reactions, providing quick feedback while keeping the device structure simple
3Measurement precision
If density meter or liquid chromatography is used for measurement, then measurement accuracy is achieved, but device is bulky and very high cost
Solution Approach 1:
The patent combines flow rate measurement and concentration measurement into a single integrated thermal sensing device. By merging these functions and using thermal properties of the fluid, the patent achieves measurement accuracy comparable to bulky instruments while dramatically reducing device size and cost
Solution Approach 2:
The thermal sensing device performs multiple measurement functions (flow rate, concentration, and potentially other fluid properties) using a single integrated sensor system. This multi-functionality eliminates the need for separate bulky instruments, reducing both device complexity and cost while maintaining measurement precision
4Adaptability or versatility
If additional sensors are integrated to measure physical properties of fluids, then measurement capability is enhanced, but sensor footprint increases and manufacturing cost increases
Solution Approach 1:
The thermal sensing system is designed to measure multiple fluid properties (flow rate, concentration, and other physical properties) using the same thermal sensors. This multi-functional approach enhances measurement capability without increasing sensor footprint or manufacturing cost, as the thermal sensors serve multiple purposes simultaneously
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 high-resolution, accurate, and reliable measurements of fluidic flow rate and concentration, enhancing process control and reducing costs by eliminating the need for multiple devices, with the capability to operate at low power and support battery supply, suitable for various applications including fuel cells and diesel engine exhaust management.
Implementation Method 1
using thermal sensing principles and a microheater
Implementation Method 2
A micro-machined thermal time-of-flight sensor integrated with a thermal diffusivity sensor
Implementation Method 3
thermal diffusivity sensor
Data Source
AI summary
The design and structure of a fluidic concentration metering device with a full dynamic range utilizing micro-machined thermal time-of-flight sensing elements is exhibited in this disclosure. With an additional identical sensing chip but packaged at the different locations in the measurement fluidic chamber with a closed conduit, the device can simultaneously measure the fluidic concentration and the fluidic flowrate. With a temperature thermistor integrated on the same micro-machined thermal sensing chip, the disclosed device will be able to provide the key processing parameters for the fluidic applications.