Microneedle Open Channel Cross-Sectional Geometry for Drug Delivery
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Solution Overview
Problem
Current drug delivery methods through the skin face challenges such as pain, local skin damage, bleeding, risk of infection, imprecision in location and dosage, and inefficiencies in delivering drugs due to the barrier function of the stratum corneum, particularly with microneedle devices that rely on active mechanisms leading to excessive drug flow beyond absorption rates.
Innovation Solution
A drug delivery device featuring a microneedle assembly with open channels of specific cross-sectional geometries that facilitate passive fluid flow, utilizing capillary forces to ensure complete wicking and absorption of the drug formulation, with a normalized hydraulic radius between 0.1 and 0.8, and interfacial energies that promote self-draining characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If active mechanisms (pumps, springs, pressuring mechanisms) are used to deliver drug formulation through microneedles, then the drug delivery rate is increased, but the flow rate becomes far greater than the absorption rate of the skin, causing drug to flow upwards to the skin surface and reducing delivery precision
Solution Approach 1:
The patent replaces active mechanical mechanisms (pumps, springs, pressuring mechanisms) with passive capillary action. The open channels in microneedles are designed with specific cross-sectional geometries that enable spontaneous wicking of drug formulation through capillary forces, eliminating the need for mechanical actuation and preventing excessive flow rates that cause drug to reach the skin surface.
Solution Approach 2:
The patent changes the physical parameters of the channel geometry, specifically designing open channels with normalized hydraulic radius between 0.01 and 0.1, and controlling the relationship between liquid-to-solid interfacial energy and liquid-to-vapor interfacial energy. These parameter changes optimize capillary wicking to match skin absorption rates, ensuring precise drug delivery without overflow.
2Reliability
If conventional needle methods are used to overcome the barrier function of stratum corneum, then drug delivery through skin is achieved, but pain, local skin damage, bleeding, and risk of infection occur
Solution Approach 1:
The patent segments the single large needle approach into multiple microneedles with open channels. This segmentation allows the device to penetrate the stratum corneum effectively while minimizing damage to deeper skin layers, reducing pain, bleeding, and infection risk associated with conventional needle injection.
Solution Approach 2:
The patent employs open channel structures within microneedles that function as porous pathways for drug formulation. These open channels allow controlled fluid transport through capillary action, enabling effective drug delivery through the skin barrier without the harmful effects of conventional solid needle injection.
3Measurement precision
If drugs are diluted to enable handling of proper dosages, then dosage precision is improved, but storage and delivery problems arise
Solution Approach 1:
The patent utilizes capillary hydraulic principles to deliver undiluted or concentrated drug formulations through open channels. The capillary forces naturally regulate the flow rate to match skin absorption rates, eliminating the need for dilution while maintaining precise dosage control and improving storage stability.
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 controlled and precise delivery of drugs, enhancing bioavailability by ensuring the drug formulation is effectively wicked along the entire length of the microneedles, reducing waste and improving absorption rates while minimizing skin irritation.
Implementation Method 1
open channels that provide for enhanced wicking of a drug formulation within the microneedles
Implementation Method 2
a liquid-to-solid interfacial energy and a liquid-to-vapor interfacial energy when a fixed volume of the drug formulation is received therein
Data Source
AI summary
In one aspect a drug delivery device may include a reservoir containing a liquid drug formulation and a microneedle assembly in fluid communication with the reservoir. The microneedle assembly may include a plurality of microneedles, with each microneedle defining an open channel for receiving a drug formulation. The open channel may have a normalized hydraulic radius ranging from about 0.1 to about 0.8. The open channel may also have a liquid-to-solid interfacial energy and a liquid-to-vapor interfacial energy when a fixed volume of the drug formulation is received therein. In addition, the drug formulation and a cross-sectional geometry of the open channel may be selected and configured such that the liquid-to-solid energy exceeds the liquid-to-vapor energy as the length of the fixed volume of drug formulation is increased within the open channel.