Piezoelectric Contact Sensor for Uniform Fluid Dispensing

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Solution Overview

Problem

Existing fluid dispensing systems face challenges in maintaining a constant distance between the dispenser and the substrate, especially when the substrate has imperfections or is not perfectly level, leading to non-uniform deposition of fluid, particularly in the fabrication of biological microarrays.

Innovation Solution

A device utilizing a piezoelectric element attached to a contact object, which measures changes in electrical properties such as impedance, resistance, capacitance, and phase to detect the point of contact and map the topography of the substrate, allowing for automatic adjustments to maintain consistent dispensing and monitor fluid levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the dispenser operates over a large area on an imperfect or non-level substrate, then productivity increases, but manufacturing precision deteriorates due to inability to maintain constant distance

Engineering Contradiction:

Improvedispensing area coverageVSAvoiddeposition uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system dynamically adjusts the dispenser height in real-time based on feedback from the contact sensor. The height adjustment mechanism transforms a static positioning system into a dynamic one that adapts to surface variations, allowing the dispenser to maintain optimal distance across large areas while preserving deposition precision.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

A contact sensor provides continuous feedback about the distance between the dispenser and substrate surface. This feedback signal is used by the control system to automatically adjust the dispenser height, creating a closed-loop control system that maintains constant distance despite surface imperfections or large area variations.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If automatic height adjustment is implemented to maintain constant distance, then manufacturing precision improves, but device complexity increases

Engineering Contradiction:

Improvedeposition uniformityVSAvoidsystem structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical positioning systems with a simpler system combining a contact sensor and automated height adjustment. Instead of using elaborate mechanical mechanisms to maintain precise distance, the system uses electrical sensing and automated control, reducing mechanical complexity while improving precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the operational parameters of the dispenser by dynamically adjusting height based on sensor feedback. This parameter adjustment approach allows precision improvement without requiring complex fixed mechanical structures, as the system adapts through controlled parameter changes rather than complex hardware.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If contact sensor is used to detect surface contact, then measurement precision improves, but the substrate may be damaged

Engineering Contradiction:

Improvecontact detection accuracyVSAvoidsubstrate damage

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The contact sensor is designed to detect contact at a threshold level that is sufficient for precise measurement but below the level that would cause damage to delicate substrates. By using partial action (light contact rather than firm contact), the system achieves measurement precision while minimizing harmful effects on the substrate.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The contact sensor acts as an intermediary between the dispenser and substrate, providing contact detection without requiring the dispenser itself to make direct contact. This intermediary approach allows precise measurement while isolating the substrate from potential damage caused by direct dispenser contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 precise detection of contact and surface topography, allowing for automatic height adjustments and accurate fluid measurement, ensuring uniform deposition and minimizing damage to delicate substrates, while effectively monitoring fluid levels in dispensing systems.

Implementation Method 1

Certain materials called piezoelectrics will expand or contract when exposed to an electrical potential, and will also generate an electric potential when deformed.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

By applying an alternating current to a piezoelectric element, it can be made to vibrate. Impedance can be used as an electrical measure of the mechanical response of piezoelectric element to a specific frequency of alternating current.

Methodology Applied

Scientific EffectPiezoelectric vibration: Piezoelectric Effect

Data Source

PatentUS7849738B2Device for detecting interaction with an object

Publication Date: 2010.12.14 SONOPLOT

AI summary

A device and method for the detection of the interaction between two or more objects is disclosed. The device utilizes electrical impedance spectra measured from a piezoelectric element attached to one such object. Comparison of such spectra along a range of traverse allows precise estimates of distance to be made. One useful application is the topographical mapping of a surface.