Acoustic Droplet Generator for Liquid Sample Introduction
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Solution Overview
Problem
Current liquid sample introduction systems for analytical instruments are inefficient due to the need for sample dilution, internal standard addition, and the inefficiency of nebulizers in producing small droplets, leading to increased analysis time and memory effects from deposited material, which limits sample throughput and requires additional handling steps and washing cycles.
Innovation Solution
The use of two droplet-on-demand generators to create streams of droplets from different liquids, which are then combined and entrained in a gas stream for direct introduction into an analysis device without contacting any surfaces, allowing for simultaneous analysis and eliminating the need for additional mixing devices and washing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a nebulizer is used to generate droplets, then a stream of droplets is produced for analysis, but the droplet size distribution is wide and large droplets are inefficiently dissociated
Solution Approach 1:
The patent replaces the mechanical nebulizer system with an acoustic field-based droplet generation system. Acoustic energy is used to levitate and manipulate droplets without mechanical contact, enabling precise control of droplet size and eliminating the wide size distribution problem inherent in mechanical nebulization.
Solution Approach 2:
The patent changes the physical parameters of droplet generation by using acoustic frequency and intensity to control droplet formation. By adjusting acoustic parameters, monodisperse droplets of specific sizes can be generated, replacing the random size distribution produced by mechanical nebulizers.
2Reliability
If a spray chamber is placed between the nebulizer and torch to filter large droplets, then large droplets are excluded from the sample stream, but only 1-2% of nebulized liquid is in the form of sufficiently small droplets
Solution Approach 1:
The patent performs preliminary droplet size selection by generating monodisperse droplets of the exact required size before they enter the analysis system. This eliminates the need for subsequent filtering in a spray chamber, as the droplets are already optimized for efficient dissociation in the plasma or flame.
Solution Approach 2:
The patent extracts the droplet size control function from the downstream spray chamber filtering process and moves it to the upstream droplet generation stage. By generating correctly-sized droplets from the start, the system eliminates the inefficient filtering step that currently discards 98-99% of nebulized liquid.
3Ease of operation
If sample is transported through tubing and contact surfaces to the droplet generator, then sample can be delivered to the analysis device, but memory effects occur from deposited material on surfaces
Solution Approach 1:
The patent replaces mechanical contact-based sample transport (tubing and surfaces) with acoustic field-based droplet manipulation. Droplets are levitated and transported through acoustic fields without touching any surfaces, eliminating the source of memory effects and cross-contamination while maintaining sample delivery capability.
Solution Approach 2:
The patent introduces acoustic fields as an intermediary medium to transport and manipulate droplets. Instead of direct contact between sample and solid surfaces, the acoustic field acts as a non-contact mediator that can precisely position and deliver droplets to the analysis device without leaving residues.
4Reliability
If additional washing cycles are performed to reduce memory effects, then deposited material is washed away, but analysis time increases
Solution Approach 1:
The patent extracts the source of memory effects (surface contact and material deposition) by eliminating surface contact in the sample transport path. Without surfaces to deposit material on, there is no memory effect to wash away, making washing cycles unnecessary and reducing total analysis time.
5Adaptability or versatility
If mixing is performed in vessels or at locations between vessels and droplet generator, then samples and standards can be combined, but additional liquid handling devices and vessels are required
Solution Approach 1:
The patent merges the mixing function with the droplet generation and transport system. By generating droplets on-demand and controlling their release timing, samples and standards can be mixed in the gas phase or through precise temporal sequencing of droplet ejection, eliminating the need for separate mixing vessels and liquid handling devices.
Solution Approach 2:
The patent replaces mechanical mixing in liquid phase with acoustic field-based droplet manipulation and gas-phase mixing. Droplets are generated, transported, and mixed through acoustic control and gas stream interactions, eliminating the need for mechanical stirrers, mixing vessels, and associated liquid handling complexity.
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 method significantly increases sample throughput by eliminating surface contact and reducing analysis time, while also enabling efficient mixing of samples and standards within the gas stream, thereby improving the efficiency of sample introduction and reducing the complexity of the sample handling process.
Implementation Method 1
applying acoustic energy to a quantity of liquid sample located on a solid surface of a sample support so as to eject a droplet of sample from the quantity of sample
Implementation Method 2
A gas stream is directed so as to entrain the droplet of sample and transport the droplet away from the quantity of liquid sample on the solid surface and into an analysis device
Data Source
AI summary
A method and apparatus for mixing droplets of liquid sample and droplets of a diluent and/or a standard produced by droplet-on-demand generators for use with an analysis device. Two different liquids may be introduced to an analysis device for simultaneous analysis. The method preferably comprises using a first droplet-on-demand generator to provide a first stream of droplets of a first liquid; using a second droplet-on-demand generator to provide a second stream of droplets of a second liquid; and combining the first and second streams of droplets before they enter the analysis device.