Microelectronic Thermal Valve for Continuous Capillary Micro-Thrust
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Solution Overview
Problem
Current technologies face challenges in achieving continuous and efficient fluid release at micro-scale volumes for specific periods of time, particularly in applications requiring high release velocity and reliability, such as in micro-satellite propulsion systems, where existing solutions like inkjet technology are impractical for continuous operation.
Innovation Solution
A propulsion system utilizing a capillary-controlled water nozzle with electrostatically actuated shutters and resistive heaters, which exploits surface tension and heat transfer to control fluid flow, enabling stable and repeatable thrust with high thrust-to-power ratios and efficient cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If inkjet technology is used to release small amounts of fluid, then precise micro-scale fluid release is achieved, but continuous operation at high release velocity is not possible
Solution Approach 1:
The patent changes the physical state of the fluid from liquid to vapor through controlled heating, enabling continuous release. The heater maintains the fluid in vapor state for continuous thrust, while the capillary structure controls the rate of fluid supply to maintain micro-scale release precision throughout the operation duration.
Solution Approach 2:
The invention utilizes phase transition of the fluid from liquid to vapor through resistive heating. This phase change enables continuous fluid release at high velocity by converting liquid fluid into vapor that can be continuously ejected through the capillary nozzle, overcoming the limitation of inkjet technology that requires cooling and refilling cycles.
2Speed
If heater power is increased to achieve high release velocity, then thrust performance is improved, but energy consumption increases
Solution Approach 1:
The patent exploits the latent heat of vaporization phase transition to achieve high release velocity with moderate energy input. The phase change from liquid to vapor provides a sudden expansion and velocity increase without requiring proportionally high power, as the energy is stored in the phase transition process rather than continuous heating.
Solution Approach 2:
The heater is positioned locally at the capillary inlet to create a focused heating zone where phase transition occurs. This localized heating approach concentrates energy input at the critical point of fluid transformation, achieving high release velocity at the nozzle exit while minimizing overall energy consumption in the system.
3Quantity of substance
If capillary width is reduced to improve micro-scale control, then fluid release precision is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent utilizes capillary action (a hydraulic principle) to achieve micro-scale fluid control through precisely engineered narrow channels. The capillary width is optimized to leverage surface tension and capillary pressure effects, providing precise fluid release control through passive physical mechanisms rather than active control systems, which simplifies manufacturing compared to mechanically actuated micro-valves.
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 system delivers specific impulse exceeding 80 seconds, achieving reliable thrust control with a high thrust-to-power ratio and efficient energy use, suitable for small spacecraft with minimal mass and volume constraints, while providing cooling benefits.
Implementation Method 1
a heater that is configured to heat liquid surrounding it causing a rapid vaporization
Implementation Method 2
The chamber is then refilled by the next payload by surface tension and a negative pressure caused by contraction of the vapor bubble
Implementation Method 3
The shutter assembly is electrostatically actuated using the force generated between two plates of different potential
Implementation Method 4
resistive heaters, which exploits surface tension and heat transfer to control fluid flow
Data Source
AI summary
A microfabricated valve with no moving parts. In one embodiment, the valve includes a reservoir of a liquid that is in fluid communication with an outlet channel having a throat that is less than 100 microns wide. Preferably, the channel is an elongated slit. The configuration of channel is adapted and configured such that surface tension of the liquid prevents flow out of the channel. A heater increases the temperature of the meniscus of the fluid, until a portion of the fluid is ejected from the channel. The ejection of the fluid creates both a thrusting effect and a cooling effect.