Eye Spray Nozzle Orifices for Uniform Droplet Delivery
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Solution Overview
Problem
Current eye spray devices produce broad droplet size distributions, leading to high impact and inaccurate delivery of medication, triggering blinking reflexes and wasting medication due to broad velocity distributions and high volume flow rates.
Innovation Solution
A spray device with nozzle orifices of identical size, between 1/10 and 2/10 times the product of spray length, air viscosity, and operating pressure, generating micro-jet sprays with droplets of uniform size, reducing impact force and velocity to prevent blinking reflexes, and using a manually operable pump to control discharge rates below 100 ul/sec.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If pressure swirl nozzles or hollow cone nozzles are used to generate spray, then spray coverage is improved, but droplet size distribution becomes broad and impact force increases
Solution Approach 1:
The nozzle is segmented into multiple separate orifices (e.g., 3-10 individual orifices) instead of a single large outlet. Each orifice produces a fine jet that breaks up into uniformly sized droplets. This segmentation allows coverage of a broader area while maintaining precise control over droplet size, as each small orifice generates droplets in a narrow size range (e.g., 10-20 micron) rather than the broad distribution from conventional nozzles.
Solution Approach 2:
Each orifice in the nozzle is designed with specific local geometry (e.g., circular cross-section, controlled diameter between 5-50 micron) to produce jets with consistent local properties. The uniform local quality of each orifice ensures that all droplets throughout the spray have similar size and velocity characteristics, preventing the broad distribution and high impact forces associated with conventional nozzles that have varying flow paths and outlet geometries.
2Productivity
If high volume flow rate is used to deliver medication, then delivery speed is improved, but blink reflex is triggered and medication is wasted
Solution Approach 1:
The spray is delivered as a periodic sequence of short pulses rather than continuous flow. Each pulse consists of a brief burst (e.g., 100-500 microseconds) of pressurized liquid through the orifices, creating a train of droplets. This periodic pulsed delivery allows the total volume to be spread over time, maintaining high productivity while keeping the instantaneous impact force below the threshold that triggers blink reflex (e.g., below 2×10−4 kgm/s²).
Solution Approach 2:
The nozzle operates at partial action by using multiple small orifices instead of one large outlet, delivering the required medication volume through many fine droplets rather than fewer large ones. This approach achieves the necessary delivery speed and total volume while each individual droplet has low mass and velocity, preventing the harmful blink reflex response that occurs with high-impact conventional sprays.
3Measurement precision
If droplet velocity is increased to reach target accurately, then delivery precision is improved, but impact force increases and triggers blinking
Solution Approach 1:
The total momentum required for accurate target delivery is segmented across many small droplets instead of concentrated in fewer large droplets. Each droplet from the micro-orifices has low individual momentum, resulting in low impact force that avoids triggering blink reflex. However, the collective momentum of all droplets together achieves the necessary delivery precision and penetration to reach the target accurately, as the fine droplets can be precisely directed and distributed over the target area.
Solution Approach 2:
The nozzle parameters (orifice diameter, number of orifices, outlet geometry) are specifically changed to produce droplets with optimized velocity and size characteristics. By controlling orifice diameter to be small (5-50 micron) and using appropriate pressurization, the system generates droplets with velocity sufficient for accurate delivery (e.g., 10-50 m/s initial velocity) but with mass small enough that the impact force remains below the blink reflex threshold. The parameter changes in droplet size and velocity distribution allow simultaneous achievement of delivery precision and low impact force.
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 device achieves a low impact, uniform spray with droplets hitting the target at a reduced terminal velocity, minimizing the blink reflex and ensuring accurate and efficient delivery of medication, with a force of spray impact below 2×10−4 kgm/s2 and a discharge rate less than 200 ul/sec.
Implementation Method 1
pressurizing means configured for pressurizing a quantity of liquid to an elevated operating pressure P, and forcing the liquid at the elevated pressure P through a plurality of nozzle orifices
Implementation Method 2
nozzle orifices of identical size... generating micro-jet sprays with droplets of uniform size
Data Source
AI summary
A spray device for delivering a liquid spray, having a spray length, through air to a target, in particular an eye, comprises a container for holding a liquid, means for pressurizing a quantity of said liquid to an elevated operating pressure, and comprises a nozzle member that comprises a nozzle plate with a plurality of nozzle orifices of substantially identical size, extending through said nozzle plate and communicating with said means to receive a quantity of pressurized liquid at said operating pressure. Said nozzle orifices discharge said liquid spray at an outlet surface of said nozzle member member over said spray length Their substantially identical size is between lower and upper limits (Dmin), (Dmax),wherein said lower limit is approximately:Dmin≈1/10LλΔP/ρ,wherein said upper limit is approximately:Dmax≈1/102LλΔP/ρ.λ≈18 η/ρ, η=1,8.10−5 kg/ms, representing the viscosity of air and ρ representing a density of said liquid.