Electrically actuated valves made from shape memory alloy wires embedded in elastomer

• US 8,002,235 B2
• Filed: 09/11/2007
• Issued: 08/23/2011
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Situala, Suresh, Vyawahare, Saurabh, Adalian, Dvin, Scherer, Axel
• Primary Examiner(s): Fristoe, Jr.; John K
• Application Number:
  US11/853,531
• Publication Number:
  US 20080173833A1
• Time in Patent Office: 1,442 Days
• Field of Search: 251/11, 251/129.01, 251/129.06, 251/331
• US Class Current: 251/11
• CPC Class Codes: C08L 2201/12 Shape memory
• CPC Class Codes: F16K 2099/0078 using moulding or stamping
• CPC Class Codes: F16K 2099/0084 Chemistry or biology, e.g. "lab-on-a-chip" technology
• CPC Class Codes: F16K 99/0001 Microvalves microdevices B81B1/00; manufacture or treatment of devices or systems in or on a substrate B81C1/00; microfluidic structures B01L3/5027; micropumps F04B19/006
• CPC Class Codes: F16K 99/0015 Diaphragm or membrane valves
• CPC Class Codes: F16K 99/0034 Operating means specially adapted for microvalves
• CPC Class Codes: F16K 99/0038 using shape memory alloys
• CPC Class Codes: F16K 99/004 using radiation
• CPC Class Codes: F16K 99/0044 using thermo-electric means
• CPC Class Codes: F16K 99/0059 actuated by a pilot fluid

Abstract

Microfluidic valves constructed from elastomeric materials as the valve body components and employing shape memory alloy in wire form as the valve actuator. Various configurations of individual valves having both normally open and normally closed states are described. Apparatus using such valves and providing logic functionality with fluidic logic outputs are discussed. Apparatus that can be used for materials processing at the nano- or micro-scale are presented. Various forms of logical control of valve arrays are explained.

Claims

1. A microfluidic valve for controlling a flow of a fluid, comprising

a substrate having at least two tie down points;

adjacent said substrate, a microfluidic valve body constructed from an elastomeric material, said valve body having a flow channel configured to have therein a valve seat and a valve piston, said valve seat and said valve piston having a first relative position wherein said flow channel is in a first state and a second relative position wherein said flow channel is in a second state different from said first state;

an actuator constructed from a shape memory alloy material, said actuator being attached at two of said at least two tie down points, said actuator configured to move said valve piston relative to said valve seat in response to an actuation signal so as to change the state of said flow channel from one of said first and second states to the other of said first and second states;

a power supply configured to actuate said microfluidic valve;

a supply of fluid configured to provide a flow though said microfluidic valve when at least partially open, and configured to provide a pressure at said microfluidic valve when closed;

a control module configured to apply control signals to said power supply, and configured to supply control signals to said supply of fluid by way of a control channel; and

a pneumatic valve responsive to a condition of said control channel, said pneumatic valve configured to control a state of said flow channel, wherein said actuator of said microfluidic valve for controlling said flow of said fluid is situated at a distance from said flow channel, said distance calculated to limit a change in temperature of said actuator from affecting a thermal condition in said flow channel;

wherein said microfluidic valve provides fluidic logic signals as output in response to control signals applied by said control module.

2. The microfluidic valve for controlling a flow of a fluid of claim 1, wherein said first state and said second state are selected from the group consisting of a fully open state, a partially open state, and a closed state.

3. The microfluidic valve for controlling a flow of a fluid of claim 1, wherein the actuator is attached to at least one tie down location with solder.

4. The microfluidic valve for controlling a flow of a fluid of claim 1, wherein said actuator constructed from said shape memory alloy material is a wire.

5. The microfluidic valve for controlling a flow of a fluid of claim 1, wherein said actuation signal is an electrical signal.

6. The microfluidic valve for controlling a flow of a fluid of claim 1, wherein said actuation signal is an illumination signal.

7. The microfluidic valve for controlling a flow of a fluid of claim 1, further comprising a block situated between said actuator and said flow channel, said block configured to transmit a force to said flow channel in response to said actuation signal.

8. The microfluidic valve for controlling a flow of a fluid of claim 1, wherein at least one of said valve seat and said valve piston is a wall of said flow channel.

9. The microfluidic valve of claim 1, further comprising:

in said microfluidic valve for controlling a flow of a fluid, a block situated between an actuator and a flow channel, said block configured to transmit a force to said flow channel in response to an actuation signal.

10. The microfluidic valve of claim 1, wherein

said actuator is configured to operate a plurality of said microfluidic valves simultaneously in response to a single actuation signal.

11. An apparatus for performing material processing operations in a microfluidic environment, comprising:

at least one microfluidic valve for controlling a flow of a fluid;

said at least one microfluidic valve comprising a substrate having at least two tie down points;

adjacent said substrate, a microfluidic valve body constructed from an elastomeric material, said valve body having a flow channel configured to have therein a valve seat and a valve piston, said valve seat and said valve piston having a first relative position wherein said flow channel is in a first state and a second relative position wherein said flow channel is in a second state different from said first state;

an actuator constructed from a shape memory alloy material, said actuator being attached at two of said at least two tie down points, said actuator configured to move said valve piston relative to said valve seat in response to an actuation signal so as to change the state of said flow channel from one of said first and second states to the other of said first and second states;

a power supply configured to actuate said at least one microfluidic valve;

at least one supply of fluid configured to provide a flow though said at least one microfluidic valve when at least partially open, and configured to provide a pressure at said at least one microfluidic valve when closed, said supply of fluid containing material to be processed;

a control module configured to apply control signals to said power supply, and configured to supply control signals to said supply of fluid by way of a control channel; and

a pneumatic valve responsive to a condition of said control channel, said pneumatic valve configured to control a state of said flow channel, wherein said actuator of said one of said at least one microfluidic valve for controlling said flow of said fluid is situated at a distance from said flow channel, said distance calculated to limit a change in temperature of said actuator from affecting a thermal condition in said flow channel.

wherein said microfluidic apparatus provides processed fluid as output in response to control signals applied by said control module.

12. The apparatus for performing material processing operations in a microfluidic environment of claim 11, further comprising:

in at least one of said at least one microfluidic valve for controlling a flow of a fluid, a block situated between an actuator and a flow channel, said block configured to transmit a force to said flow channel in response to an actuation signal.

13. The apparatus for performing material processing operations in a microfluidic environment of claim 11, wherein said actuator is configured to operate a plurality of said microfluidic valves simultaneously in response to a single actuation signal.

14. The apparatus for performing material processing operations in a microfluidic environment of claim 11, further comprising:

a sensor configured to sense an output signal from said at least one processed fluid, said output signal representative of information derived from said processed fluid and having significance to a user of said apparatus; and

an output module configured to perform at least one of recording and displaying said output signal representative of information derived from said processed fluid and having significance to a user of said apparatus.