Pipette Tip Impedance Sensor for Dead Volume Elimination
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Solution Overview
Problem
Existing pipette designs lack the ability to detect and analyze particles within a fluid without a dead volume, making it difficult to analyze small numbers of particles and resulting in particle loss during detection.
Innovation Solution
A sensing tip with electrodes located at the tip aperture eliminates dead volume, allowing for real-time detection and analysis of particles by establishing an electric field through the aperture, enabling impedance spectroscopy and Coulter counting, and is fabricated using a dielectric membrane and conductive electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is located in the fluid path away from the tip extremity, then the sensor can detect particles, but a dead volume is created between the tip and sensor making single particle analysis impossible
Solution Approach 1:
The sensing area is extracted and positioned exactly at the tip aperture where particles enter, removing the dead volume that existed between the tip and sensor in conventional designs. This allows immediate detection of particles as they enter the tip without requiring accumulation in a separate sensing chamber.
Solution Approach 2:
The sensing mechanism transitions from a volumetric detection approach (requiring particles to fill a sensing chamber) to a surface/aperture-based detection approach, where the sensing area is positioned at the two-dimensional aperture plane, eliminating the need for particle accumulation in three-dimensional dead volume.
2Quantity of substance
If a dead volume is present in the fluid path, then particles can be accumulated for detection, but particles are lost after detection making the design unsuitable for particle dispensing
Solution Approach 1:
The dead volume is completely removed from the system by positioning the sensing area at the tip aperture. Particles are detected immediately upon entry without being stored in a separate volume, eliminating the source of particle loss while maintaining detection capability.
Solution Approach 2:
Particle detection occurs at the very moment of tip immersion and particle entry, performing the detection action preliminarily before any possibility of particle loss can occur. This real-time detection at the aperture prevents subsequent particle loss that would occur in dead volume designs.
3Quantity of substance
If a sufficient number of particles are required to fill the dead volume, then the sensor can detect particles, but analysis of small number of particles becomes impossible
Solution Approach 1:
The requirement for particle accumulation is extracted and eliminated by positioning detection at the aperture. Single particles detected at the tip entrance do not need to fill a dead volume, enabling precise analysis of small particle samples including single-cell analysis.
Solution Approach 2:
Instead of requiring full accumulation of particles to fill the dead volume, the system detects particles at the aperture level with minimal particle presence, using partial action (detecting particles as they arrive) rather than requiring excessive particle accumulation.
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
Enables the precise detection and analysis of single particles with minimal loss, allowing for accurate characterization and dispensing of particles without the need for filling a dead volume, improving the analysis of small particle samples.
Implementation Method 1
The sensor is based on electrical impedance sensor
Implementation Method 2
A method to detect particles in a fluid was first described in the Coulter counter design
Data Source
AI summary
A sensing tip including a pipette tip having a cavity which communicates with an external environment of the pipette tip through an aperture located at a distal end of the pipette tip, and an impedance sensor having a sensing area including at least two electrodes located respectively outside and inside the pipette tip, wherein the sensing area is arranged within the aperture.