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WO2002018827A1 - Valves microfluidiques - Google Patents

Valves microfluidiques Download PDF

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Publication number
WO2002018827A1
WO2002018827A1 PCT/US2001/027322 US0127322W WO0218827A1 WO 2002018827 A1 WO2002018827 A1 WO 2002018827A1 US 0127322 W US0127322 W US 0127322W WO 0218827 A1 WO0218827 A1 WO 0218827A1
Authority
WO
WIPO (PCT)
Prior art keywords
micro
conduit
valve according
fluidic
valve
Prior art date
Application number
PCT/US2001/027322
Other languages
English (en)
Inventor
Robert W. Hower
Hal C. Cantor
Jason R. Mondro
Original Assignee
Advanced Sensor Technologies
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Advanced Sensor Technologies filed Critical Advanced Sensor Technologies
Priority to US10/362,329 priority Critical patent/US20040011977A1/en
Priority to AU2001288657A priority patent/AU2001288657A1/en
Publication of WO2002018827A1 publication Critical patent/WO2002018827A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K99/0001—Microvalves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15C—FLUID-CIRCUIT ELEMENTS PREDOMINANTLY USED FOR COMPUTING OR CONTROL PURPOSES
    • F15C3/00—Circuit elements having moving parts
    • F15C3/04—Circuit elements having moving parts using diaphragms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15C—FLUID-CIRCUIT ELEMENTS PREDOMINANTLY USED FOR COMPUTING OR CONTROL PURPOSES
    • F15C5/00—Manufacture of fluid circuit elements; Manufacture of assemblages of such elements integrated circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K99/0001—Microvalves
    • F16K99/0003—Constructional types of microvalves; Details of the cutting-off member
    • F16K99/0015—Diaphragm or membrane valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K99/0001—Microvalves
    • F16K99/0034—Operating means specially adapted for microvalves
    • F16K99/0036—Operating means specially adapted for microvalves operated by temperature variations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K99/0001—Microvalves
    • F16K99/0034—Operating means specially adapted for microvalves
    • F16K99/0055—Operating means specially adapted for microvalves actuated by fluids
    • F16K99/0061—Operating means specially adapted for microvalves actuated by fluids actuated by an expanding gas or liquid volume
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K99/0001—Microvalves
    • F16K2099/0069—Bistable microvalves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K2099/0073—Fabrication methods specifically adapted for microvalves
    • F16K2099/0074—Fabrication methods specifically adapted for microvalves using photolithography, e.g. etching
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K2099/0073—Fabrication methods specifically adapted for microvalves
    • F16K2099/0076—Fabrication methods specifically adapted for microvalves using electrical discharge machining [EDM], milling or drilling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K2099/0073—Fabrication methods specifically adapted for microvalves
    • F16K2099/008—Multi-layer fabrications
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K2099/0082—Microvalves adapted for a particular use
    • F16K2099/0084—Chemistry or biology, e.g. "lab-on-a-chip" technology

Definitions

  • actuators are the driving mechanism behind valves that selectively control the flow of fluid through a passageway, channel, port, or the like, in various micro-fluidic devices and systems. These actuators work by various types of actuation forces applied to a flexible mechanism, valve or other similar device. Actuation occurs through methods using various forces such as electrostatic, piezoresistive, pneumatic, magnetic, and thermal gas expansion.
  • micro-fluidic valves Most, if not all, of the micro-fluidic valves are used on structures that are not planar. (See, U.S. Patents 5,962,081 and 5,726,404).
  • Various other efforts are also underway to build miniature valves in silicon for micro-fluidics. It has been difficult to produce good sealing surfaces in silicon, and it turns out that these valves, although in principle can be mass-produced on a silicon wafer, they require expensive packaging to be utilized. Consequently, such micro-fluidic components cannot be considered inexpensive and/or disposable.
  • these micro-fluidic valves should have the capability to be interconnected into systems including sensors, electronic controls, telemetric circuitry, and other devices such that the interconnection becomes expensive.
  • Figure 1 is a schematic view of an embodiment of a mono-stable valve
  • FIG. 5 graphically shows the temperature profile of wax cooling at different times
  • expanding mechanism 14 as used herein, is meant to include, but is not limited to, a fluid 14 capable of being vaporized and condensed within a closed cavity 11.
  • the expanding mechanism 14 operates upon being actuated or heated.
  • the expanding mechanism 14 includes, but is not limited to, water, wax, hydrogel, hydrocarbon, and any other similar substance known to those of skill in the art.
  • the micro-fluidic valve 22 has various pressures and temperatures required for its actuation.
  • the valve 22 can be selectively controlled and actuated through an integrated CMOS circuit or through computer control, which controls actuation timing, electrical current, and heat generation/dissipation requirements for actuation. Integration of control circuitry is important for reduced power requirements of the present invention.
  • sensors and circuitry responsible for monitoring the effluent of a fuel cell, with concomitant control of the micro- fluidic fuel delivery system to increase or decrease the flow rate of fuel is designed. This ensures optimal fuel utilization in the device. Closed loop feedback provides the basis of automated adjustment of circuitry and therefore, valving, within the micro actuator.
  • the actuator 10 includes a closed cavity 11 , flexible mechanism 18, and expanding mechanism 14.
  • the expanding mechanism 14 selectively expands the cavity 11 defined by the flexible mechanism 18 thereof and thereby selectively flexes the flexible mechanism 14.
  • the expanding mechanism can be made of various materials.
  • the expanding mechanism is a hydrogel material, which contains a large amount of water or other hydrocarbon medium, which is vaporized by the underlying heating mechanism.
  • the volume of hydrogel needed to produce the desired actuation and pressure for the flexible mechanism 18 is approximately 33 pL. With this design, approximately 97% of the energy generated by the heating mechanism 12 is transferred into the hydrogel for evaporation.
  • the heat flux through each of the layers composing the device is calculated using existing boundary conditions.
  • the temperature required to vaporize the expanding mechanism 14 varies according to the physical and chemical properties of the expanding mechanism 14 itself. Due to the differences in heat transfer through liquid versus gas, approximately twice as much heat flux travels through the device when the hydrogel is all liquid compared to all vapor. In order to reduce heat dissipation into the medium being valved, while the hydrogel is in the liquid state, the heating mechanism 12 is quickly ramped. to the temperature required to vaporize the liquid. Once the hydrogel is vaporized, heat transfer to the medium being valved is minimized.
  • the temperature on both sides of the SiO 2 that encapsulates the heating mechanism 12 is constant, and that heat flux in each direction is dependent upon the heating mechanism 12 temperature and the resistance to heat flow either through the device or to the air from the backside.
  • a cavity is etched in the backside of the wafer, providing thermal isolation.
  • the temperature of the saturated liquid hydrogel, at 1 ATM is assumed to be 100°C.
  • the heat flux to the air, through the back of the heating mechanism 12, is calculated to be 1263 W/K-m 2 .
  • the total heat flux through the device is calculated to be 46,995 W/K-m 2 with a total flux from the heating mechanism 12 of 47,218 W/K-m 2 (i.e. 97% efficiency of focused heat transfer).
  • the temperature of the inactive state hydrogel varies between 86 and 94 C.
  • the heat transfer coefficient for convection can be calculated directly from the thermal conductivity.
  • the heat flux to the air through the back of the heating mechanism 12 is 2818 W/K-m 2 .
  • the heat flux through the device is 21 ,352 W/K-m 2 with a total flux from the heating mechanism 12 of 24,170 W/K-m 2 .
  • the aqueous component of the hydrogel is completely in the vapor state, there is no fluid 14 in the channel and the thin film of solution between the flexible mechanism 18 and the glass is approximately at 60°C.
  • the volume of liquid hydrogel is determined based on the volume of vapor needed to expand the flexible mechanism 18 completely at, 2 ATM, using the ideal gas law. This assumption is valid because the temperatures and pressures are moderate.
  • the volume of liquid hydrogel necessary to achieve this volume of gas at this pressure assuming the hydrogel is 10% water and all of the water is completely evaporated, is 0.033 nL.
  • Cylindrically shaped sections of hydrogel are utilized within the actuator 10. This shape has been chosen to optimize encapsulation by the actuator flexible mechanism 18.
  • the cylinders have either a diameter of approximately 140 ⁇ m and a height of 2.14 ⁇ m, or a diameter of 280 ⁇ m with a height of 0.54 ⁇ m (identical volumes, different orientation to the heating element).
  • the shapes and volumes vary according to the type of expanding mechanism being used. For example, photocurable liquid hydrogels have different parameters.
  • FIG. 1 is a schematic layout of an actuator 10 and heating mechanism 12.
  • the heating mechanism 12 is poly-silicon, but can be any similar material. Because of its high thermal conductivity, the silicon substrate acts as a heat sink.
  • the second method involves dispensing liquid hydrogel into well-rings created around the poly-silicon heating mechanism 12. These wells have the ability to retain a liquid in a highly controlled manner.
  • Two photopatternable polymers have been utilized to create microscopic well-ring structures, SU-8 and a photopatternable polyimide. These well-rings can be produced in any height from 2 ⁇ m to 50 ⁇ m, sufficient to contain the liquid hydrogel. Once the hydrogel solidifies, flexible mechanisms can be deposited over them. This can be accomplished in an automated manner utilizing commercially available dispensing equipment.
  • a mono-stable valve 22 requires continuous power to maintain a closed-stated position. Utilizing the heating mechanism 12, an expanding mechanism 14 is vaporized under the encapsulating flexible mechanism 18 thereby providing the pneumatic driving force required to expand the flexible mechanism 18 and hence occluding the micro conduit 20.
  • the mono-stable, normally , open valve utilizes a single actuator to effectively actuate the valve. As the hydrogel is expanded, the silicone rubber of the actuator completely occludes the micro-fluidic channel to effect valving of the solution. Schematics of the mono-stable valves are presented in Figure 1 and 4. While the normally open valve is less complicated to construct, it requires continuous power or pulsed power to keep the valve closed.
  • a bi-stable valve is designed that utilizes lower power consumption for valves that remain in the same state for long periods and a wax material to provide passively open and passively closed functionality, i.e. bi-stability.
  • the bi-stable valve design is based upon the utilization of a moderate melting point solid, such as paraffin wax, which possesses a melting point between 50 and 70 C.
  • Figure 2a shows a top view and 2b shows a cross-section of the bi-stable valve in the open state.
  • the two actuators on the left, which contain the paraffin wax, are connected to each other by a fluid conduit.
  • the bi-stable valve utilizes a total of three micro-fluidic actuating mechanisms 10, 15.
  • any number of actuating mechanisms 10, 15 can be used without departing from the spirit of the present invention.
  • Two actuating mechanisms 15 are physically connected by a micro-fluid conduit formed under the membrane, and are filled with a low melting point solid such as paraffin wax as opposed to an aqueous, hydrogel 14 (see above for mono-stable actuation).
  • the third is a standard design micro-actuator 10 filled with an aqueous hydrogel connected by the expansion chamber to the middle wax filled actuator. The first two micro- actuators 15 are activated causing the wax to melt.
  • Actuation of the micro-fluidic bi-stable valve entails melting of a paraffin wax beneath an actuating membrane, and using pressure to force it into a hemispherical chamber to occlude a fluidic channel, hence closing the valve.
  • the hydrogel-based actuator provides the pressure. After the wax is allowed to cool, the valve remains closed without external power. To open the valve, the wax is again melted allowing it to re-flow into its original position, forced by tension on the expanded valving membrane. To calculate time required for melting and solidifying of the wax, certain assumptions are made.
  • Wax is contained in the small actuator in the left chamber, which is in the shape of a hemisphere with radius of 140 ⁇ m and a height of 20 ⁇ m when the valve is open and a height of 120 ⁇ m when the valve is closed.
  • the middle chamber has a radius of 400 ⁇ m and a height of 30 ⁇ m when the valve is open, and when closed, the wax is be forced into the small chamber leaving a height of 20.25 ⁇ m.
  • Using these dimensions to calculate the volume of wax in each chamber yields 1.23 nL of solid wax in the small chamber and 15 nL of solid wax in the middle chamber with the valve open (i.e. membranes relaxed).
  • the insulating assumption used for the small 120 ⁇ m wax slab, in the expanded valve, which blocks the fluid channel, is a conservative assumption and provides a maximum cooling time using only a convective boundary on one side of the wax. A more realistic estimate is similar to that of the constant temperature boundary condition, with the flowing solution in the channel as the constant temperature sink.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Theoretical Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Micromachines (AREA)

Abstract

L'invention concerne une valve microfluidique (10) comportant un microconduit (20) servant à transporter le fluide et au moins un micromécanisme d'actionnement (16) servant à dévier de manière sélective au moins une partie de la paroi du microconduit obstruant l'écoulement du liquide dans le microconduit. Par ailleurs, l'invention concerne une valve microfluidique monostable et une valve fluidique bistable.
PCT/US2001/027322 2000-08-31 2001-08-31 Valves microfluidiques WO2002018827A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US10/362,329 US20040011977A1 (en) 2001-08-31 2001-08-31 Micro-fluidic valves
AU2001288657A AU2001288657A1 (en) 2000-08-31 2001-08-31 Micro-fluidic valves

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US22938000P 2000-08-31 2000-08-31
US60/229,380 2000-08-31

Publications (1)

Publication Number Publication Date
WO2002018827A1 true WO2002018827A1 (fr) 2002-03-07

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2001/027322 WO2002018827A1 (fr) 2000-08-31 2001-08-31 Valves microfluidiques

Country Status (2)

Country Link
AU (1) AU2001288657A1 (fr)
WO (1) WO2002018827A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2400158A (en) * 2003-04-02 2004-10-06 Starbridge Systems Ltd Micro-fluidic thermally responsive valve
GB2414059A (en) * 2004-05-10 2005-11-16 E2V Tech Uk Ltd A valve for a microfluidic device
US7357898B2 (en) 2003-07-31 2008-04-15 Agency For Science, Technology And Research Microfluidics packages and methods of using same
CN115722278A (zh) * 2021-08-31 2023-03-03 湖南乐准智芯生物科技有限公司 微流控芯片及其检测装置、控制方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2241086A (en) * 1939-01-28 1941-05-06 Gen Motors Corp Refrigerating apparatus
US4036433A (en) * 1975-11-06 1977-07-19 Robertshaw Controls Company Thermally operated control device and method of making the same
US5546757A (en) * 1994-09-07 1996-08-20 General Electric Company Refrigeration system with electrically controlled expansion valve
US6102897A (en) * 1996-11-19 2000-08-15 Lang; Volker Microvalve
US6141497A (en) * 1995-06-09 2000-10-31 Marotta Scientific Controls, Inc. Multilayer micro-gas rheostat with electrical-heater control of gas flow
US6283440B1 (en) * 1998-11-30 2001-09-04 The Regents Of The University Of California Apparatus and method for regulating fluid flow with a micro-electro mechanical block

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2241086A (en) * 1939-01-28 1941-05-06 Gen Motors Corp Refrigerating apparatus
US4036433A (en) * 1975-11-06 1977-07-19 Robertshaw Controls Company Thermally operated control device and method of making the same
US5546757A (en) * 1994-09-07 1996-08-20 General Electric Company Refrigeration system with electrically controlled expansion valve
US6141497A (en) * 1995-06-09 2000-10-31 Marotta Scientific Controls, Inc. Multilayer micro-gas rheostat with electrical-heater control of gas flow
US6102897A (en) * 1996-11-19 2000-08-15 Lang; Volker Microvalve
US6283440B1 (en) * 1998-11-30 2001-09-04 The Regents Of The University Of California Apparatus and method for regulating fluid flow with a micro-electro mechanical block

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2400158A (en) * 2003-04-02 2004-10-06 Starbridge Systems Ltd Micro-fluidic thermally responsive valve
WO2004088148A1 (fr) * 2003-04-02 2004-10-14 Starbridge Systems Limited Dispositifs fluidiques
GB2400158B (en) * 2003-04-02 2006-03-22 Starbridge Systems Ltd Fluidic devices
US7357898B2 (en) 2003-07-31 2008-04-15 Agency For Science, Technology And Research Microfluidics packages and methods of using same
GB2414059A (en) * 2004-05-10 2005-11-16 E2V Tech Uk Ltd A valve for a microfluidic device
GB2414059B (en) * 2004-05-10 2008-06-11 E2V Tech Uk Ltd Microfluidic device
CN115722278A (zh) * 2021-08-31 2023-03-03 湖南乐准智芯生物科技有限公司 微流控芯片及其检测装置、控制方法

Also Published As

Publication number Publication date
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