MEMS Flow Control Apparatus with Dielectric Isolation
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Solution Overview
Problem
Current microfluidic devices lack efficient control over fluid flow rates and are prone to electrolysis due to electric fields, especially in applications requiring precise drug delivery and filtration, where biocompatibility and low power consumption are essential.
Innovation Solution
A microelectromechanical (MEM) flow control apparatus using a substrate with a nonconducting material forming a fluid channel, electrodes for voltage-controlled deformation, and optional submicron filters and pressure sensors to regulate fluid flow and prevent electrolysis by maintaining the channel free from electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If voltage is applied between electrodes to control fluid flow, then flow rate control is achieved, but electrolysis occurs in the fluid
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the electrode and the fluid channel. This dielectric layer allows the electrode to generate mechanical deformation for flow control while preventing direct electrical contact with the fluid, thereby eliminating electrolysis. The dielectric layer acts as a mediator that transmits mechanical effects while blocking harmful electrical effects.
Solution Approach 2:
The patent replaces direct electrical actuation of the fluid with a mechanical deformation mechanism. Instead of applying voltage directly to the fluid channel, the electrode deforms the dielectric layer which in turn deforms the fluid channel walls, controlling flow through mechanical means rather than direct electrical means, thus avoiding electrolysis.
2Ease of operation
If electric field is applied to control fluid flow, then flow regulation is achieved, but power consumption increases
Solution Approach 1:
The patent replaces continuous electrical field application with intermittent voltage pulses that create mechanical deformation. The dielectric layer and deformable channel walls store mechanical energy during deformation and release it during relaxation, reducing the average power required compared to continuous electrical actuation.
Solution Approach 2:
The flow control is achieved through periodic application of voltage to the electrode, creating cyclic deformation of the dielectric layer and fluid channel. This periodic mechanical action controls flow with lower average power consumption compared to maintaining a continuous electric field.
3Ease of manufacture
If standard micromachining processes are used, then fabrication is simplified, but device complexity increases due to multiple layers
Solution Approach 1:
The device is segmented into distinct functional layers (substrate, dielectric layer, electrode, fluid channel) that can be fabricated using separate micromachining processes. This segmentation allows each layer to be optimized and fabricated independently using standard techniques, simplifying manufacturing despite the multi-layer structure.
Solution Approach 2:
The patent employs composite structures combining different materials (dielectric material, conductive electrode material, substrate material) in layered configuration. Each material is selected for its specific properties and can be fabricated using appropriate micromachining processes, allowing complex functionality to be achieved through material composition rather than structural 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
The MEM flow control apparatus enables precise control of fluid flow rates, prevents electrolysis, and ensures biocompatibility, with low power consumption and efficient filtration of submicron particles, suitable for drug delivery and other microfluidic applications.
Implementation Method 1
The first layer of the nonconducting material can be deformed (i.e. bowed under stress) away from the substrate to increase a cross-sectional size of the fluid channel in response to a voltage applied between the first and second electrodes
Implementation Method 2
The substrate can be made electrically conductive to provide a third electrode beneath the channel. Then, when the voltage is applied between the first electrode and the substrate, the first layer of the nonconducting material can be deformed towards the substrate
Data Source
AI summary
A microelectromechanical (MEM) flow control apparatus is disclosed which includes a fluid channel formed on a substrate from a first layer of a nonconducting material (e.g. silicon nitride). A first electrode is provided on the first layer of the nonconducting material outside the flow channel; and a second electrode is located on a second layer of the nonconducting material above the first layer. A voltage applied between the first and second electrodes deforms the fluid channel to increase its cross-sectional size and thereby increase a flow of a fluid through the channel. In certain embodiments of the present invention, the fluid flow can be decreased or stopped by applying a voltage between the first electrode and the substrate. A peristaltic pumping of the fluid through the channel is also possible when the voltage is applied in turn between a plurality of first electrodes and the substrate. A MEM flow control assembly can also be formed by providing one or more MEM flow control devices on a common substrate together with a submicron filter. The MEM flow control assembly can optionally include a plurality of pressure sensors for monitoring fluid pressure and determining flow rates through the assembly.