Segmented Microneedle Electrode Assembly for Transdermal Delivery
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Solution Overview
Problem
Conventional transdermal delivery methods face challenges in rapidly and stably delivering active agents through the skin without causing irreversible damage, and are limited by the capacity of microneedles and the need for high voltages that can harm the skin, as well as being affected by skin surface conditions.
Innovation Solution
An electrode assembly with a penetrative electrode and a surface electrode of opposite polarity, where the penetrative electrode comprises microneedles with insulated shafts and conductive tips, and a dispenser for the active agent, applied with a voltage differential to facilitate transdermal delivery without passing through the microneedles, using suction to aid penetration and maintain contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electroporation uses high voltage pulses between physically separated electrodes, then transdermal delivery of active agents is achieved, but skin damage and irreversible pore damage occur
Solution Approach 1:
The electrode system is segmented into multiple microelectrodes arranged in an array, with each microelectrode having insulated shaft and conductive tip. This segmentation allows localized electric field application through individual needle tips, concentrating the electroporation effect at specific penetration points while reducing overall voltage requirements and preventing widespread skin damage.
Solution Approach 2:
The microneedles provide localized electrical contact at their tips beneath the stratum corneum, creating highly focused electric fields at the treatment site. The insulated shafts ensure that electrical energy is delivered only at the target location, enabling effective transdermal delivery with lower voltages that prevent collateral skin damage.
2Productivity
If microneedles are used for active agent delivery, then transdermal penetration is improved, but delivery capacity is limited by small lumen cross-sectional area
Solution Approach 1:
The invention extracts the electrical delivery function from the microneedle structure itself, using insulated shafts with conductive tips that apply electric fields to create pores in the stratum corneum. The active agent is then delivered through these electroporation-induced pores rather than through the microneedle lumens, bypassing the volume limitation of small needle channels.
Solution Approach 2:
The electric field acts as an intermediary mechanism that creates transient pores in the stratum corneum, enabling bulk delivery of active agents without requiring the microneedles themselves to serve as delivery conduits. This mediator approach overcomes the physical size constraints of microneedle lumens.
3Productivity
If conventional iontophoresis uses electrodes on skin surface, then pharmaceutical compound delivery is achieved, but delivery is affected by skin surface conditions
Solution Approach 1:
The electrode array is segmented into multiple discrete microelectrodes that penetrate the stratum corneum to reach deeper skin layers. This segmentation allows the system to bypass variable skin surface conditions and deliver active agents to more consistent deeper tissue targets, reducing sensitivity to surface variations.
Solution Approach 2:
The microneedles perform preliminary mechanical penetration of the stratum corneum barrier before electrical stimulation is applied. This preliminary action creates a controlled pathway through the variable skin surface layer, enabling subsequent electroporation and active agent delivery that is less affected by skin surface condition variations.
4Productivity
If voltage is increased to open skin pores for transdermal delivery, then delivery throughput increases, but skin resistance drops and irreversible damage occurs
Solution Approach 1:
The use of multiple segmented microelectrodes allows the total delivery throughput to be achieved through many small localized sites rather than requiring high voltage at a single location. Each microelectrode operates at lower voltage to create reversible pores, while the cumulative effect of multiple needles achieves high overall delivery rates without compromising skin integrity.
Solution Approach 2:
The system applies partial electroporation action at many locations simultaneously, creating numerous small pores rather than attempting to create large pores with high voltage. This distributed partial action achieves sufficient total pore formation for high throughput while maintaining skin integrity through reversible pore formation at each site.
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 efficient, stable, and reversible delivery of active agents across the stratum corneum with lower voltages, reducing skin damage and increasing delivery volume, independent of skin surface conditions, and allowing higher transdermal throughput.
Implementation Method 1
Electroporation is a technique used where an electrical field is applied to cells in order to increase the permeability of the cell membrane, thereby allowing active ingredients such as chemicals, drugs or DNA to be introduced into the cell. The principle is that an electric field generated by a high voltage pulse between two electrodes causes a transient dielectric breakdown of the plasma membrane of cells within the high intensity electric field.
Implementation Method 2
Conventional iontophoresis devices include a positive electrode and a negative electrode positioned on the surface of the skin. By using electromotive repulsion between the electrical field and the pharmaceutical compounds, the pharmaceutical compound is delivered to a blood vessel deeper in the stratum.
Data Source
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Figure 3~4
Figure 5
AI summary
A transdermal delivery system (1) configured to deliver an active agent to human or animal tissue, comprising a penetrative electrode (2) of one polarity that provides an electrical contact (3) beneath the stratum corneum (20); a surface electrode (4) of the opposite polarisation to that of the penetrative electrode (2) that provides an electrical contact to the external surface of the skin (21) on the opposite side of the stratum corneum (20) to the electrical contact (3) of the penetrative electrode (2); a dispenser (5) configured to deliver of an active agent to the external surface of the skin (21) adjacent to an electrical contact of the surface electrode (4); a method of delivering the active agent to the tissue of a human or animal body using the transdermal delivery system (1) and an electrode assembly (10) for use in preparing the transdermal delivery system (1).