EWOD Cartridge Position Sensing via Integrated Circuitry
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Solution Overview
Problem
Conventional AM-EWOD devices face challenges in achieving high-precision alignment of the cartridge relative to the instrument, leading to misalignment issues that affect the accuracy of droplet manipulation operations, particularly in applications requiring precise mechanical alignment for magnetic bead-based washing and other operations.
Innovation Solution
The system incorporates sensing circuitry within the array element circuitry to detect both internal droplets and external locators within the instrument, allowing for adjustments to the reaction protocol or script to compensate for mechanical misalignment, ensuring optimal alignment of droplet manipulation operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mechanical alignment methods are used for cartridge-instrument alignment, then the device structure is simple, but the alignment precision is insufficient leading to droplet manipulation errors
Solution Approach 1:
The patent replaces mechanical alignment systems with an electrical field-based sensing system. The sensing circuitry uses electrical fields to detect the positions of locators on the cartridge and calculate alignment offsets, eliminating the need for complex mechanical alignment mechanisms while achieving sub-pixel alignment precision.
Solution Approach 2:
The patent introduces electrical fields as an intermediary between the cartridge and instrument for alignment detection. The sensing circuitry generates electrical fields that interact with conductive locators, providing indirect measurement of positional relationships without direct mechanical contact or complex optical systems.
2Measurement precision
If high-precision mechanical alignment is implemented, then droplet positioning accuracy improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent substitutes mechanical positioning systems with an electrical sensing and software compensation system. The sensing circuitry measures actual positions of locators, and the control system calculates offset values to adjust droplet manipulation commands, achieving high positioning accuracy without mechanical complexity.
Solution Approach 2:
The patent changes the approach from physical parameter adjustment (mechanical positioning) to electrical and computational parameter adjustment. By measuring electrical properties of the sensing circuitry in response to voltage perturbations on locators, the system determines positional offsets and modifies control parameters accordingly.
3Manufacturing precision
If mechanical tolerance range is reduced for precise alignment, then alignment accuracy improves, but manufacturing cost and difficulty increase
Solution Approach 1:
The patent implements a feedback system where the sensing circuitry measures the actual positions of locators after cartridge insertion, calculates alignment offsets, and feeds this information back to the control system. The control system then compensates for misalignment by adjusting droplet manipulation commands, allowing manufacturing with standard tolerances while achieving high operational precision.
Solution Approach 2:
The patent replaces tight mechanical tolerance requirements with an electrical sensing and software compensation system. Instead of requiring精密 mechanical manufacturing, the system uses voltage perturbations and electrical field interactions to detect and compensate for positional variations, significantly easing manufacturing requirements.
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 enhances the precision of droplet positioning, reduces the volume of supernatant fluid, and minimizes the amount of sample or reagent required, thereby improving the efficacy of operations like magnetic bead-based washing and other high-precision droplet manipulations.
Implementation Method 1
having an electrically conductive locator that is external to the EWOD cartridge... applies a voltage perturbation to the locator... reads an output from the sensing circuitry in response to the voltage perturbation applied to the locator
Data Source
Figure 1~2
Figure 3~4B
Figure 5
AI summary
A microfluidic system includes: an electro-wetting on dielectric (EWOD) cartridge having an element array configured to receive liquid droplets, the element array including individual array elements each including array element circuity comprising sensing circuitry that is integrated into the array element circuitry; a microfluidic instrument that is configured to receive the EWOD cartridge and having an electrically conductive locator that is external to the EWOD cartridge; and a control system configured perform electrowetting operations by controlling actuation voltages applied to the element array to perform manipulation operations as to liquid droplets present on the element array. The control system further is configured to read an output from the sensing circuitry, determine a position of the locator relative to the element array based on the output, and determine a misalignment of the EWOD cartridge relative to the microfluidic instrument based on the position of the locator. The control system may adjust a droplet manipulation operation to compensate for the determined misalignment.