Electrically controlled contractile polymer composite

• US 6,117,296 A
• Filed: 07/21/1998
• Issued: 09/12/2000
• Est. Priority Date: 07/21/1998
• Status: Expired due to Fees

• Current Assignee: Hydrophilix LLC, Tabulatum, Inc.
• Original Assignee: Hydrophilix LLC
• Inventors: Thomson, Timothy
• Primary Examiner(s): Mayekar, Kishor
• Application Number:
  US09/121,075
• Time in Patent Office: 784 Days
• Field of Search: 204/296, 204/450.553, 204/607, 204/601, 204/602, 204/295, 205/450, 623/14
• US Class Current: 204/607
• CPC Class Codes: F03G 7/005 Electro-chemical actuators; Actuators having a material for absorbing or desorbing gas, e.g. a metal hydride; Actuators using the difference in osmotic pressure between fluids; Actuators with elements stretchable when contacted with liquid rich in ions, with UV light, with a salt solution
• CPC Class Codes: H02N 11/006 Motors

Abstract

An electrically controlled polymer composite which, when acted upon by an electric current, contracts or relaxes. It can also serve as a smart drug delivery device. The polymer composite is a series of hydrogel layers, each of which serve a particular purpose. A nonionic layer serves as a reservoir for an ionic salt while layers on either side can be anionic hydrogels and cationic gel. The invention can include an imbedded strain gauge by which the contractions or relaxations are monitored and controlled. The device is capable of being controlled by a computer with data acquisition and control capabilities.

Claims

1. A contractile apparatus comprising:

an electrical conductor;

a polymer composite in electrical communication with said conductor, said polymer composite comprising;

a nonionic polymer hydrogel containing a soluble ionic salt; and

an ionic polymer hydrogel in intimate contact with said nonionic polymer hydrogel;

means for passing a first electric current of predetermined polarity through said electrical conductor to said polymer composite to cause said soluble salt in said nonionic polymer hydrogel to pass ions to said ionic polymer hydrogel resulting in a contraction of said ionic polymer hydrogel; and

means for passing a second electrical current of predetermined and opposite polarity to the polarity of said first electrical current through said electrical conductor to said polymer composite to cause said ions from said ionic polymer hydrogel to pass to said soluble salt in said nonionic polymer hydrogel resulting in a relaxation of said ionic polymer hydrogel;

wherein both of said means result in two-way migration of said ions in said polymer composite.

2. The contractile apparatus as claimed in claim 1 further comprising a second ionic polymer hydrogel in intimate contact with said nonionic polymer hydrogel.

3. The contractile apparatus as claimed in claim 2 wherein said ionic polymer hydrogel is a cationic polymer hydrogel and wherein said second polymer hydrogel is an anionic polymer hydrogel.

4. The contractile apparatus as claimed in claim 3 wherein said soluble salt comprises a cation producing salt and an anion producing salt.

5. The contractile apparatus as claimed in claim 1 wherein said polymer composite is formed into a substantially cylindrical rod comprising a conductive core, a layer of said nonionic polymer hydrogel disposed about said core, a layer of said ionic polymer hydrogel disposed about said layer of nonionic polymer hydrogel, and a conductive coating disposed about said layer of ionic polymer hydrogel.

6. The contractile apparatus as claimed in claim 5 further comprising a second layer of ionic polymer hydrogel disposed between said conductive core and said nonionic polymer hydrogel and wherein one ionic polymer hydrogel is a cationic polymer hydrogel and another ionic polymer hydrogel is an anionic polymer hydrogel.

7. The contractile apparatus as claimed in claim 1 further comprising a colorimetric device to monitor a concentration of said soluble ionic salt.

8. The contractile apparatus as claimed in claim 7 further comprising a controller for controlling the means for passing the first and second electrical current to said polymer composite based upon said concentration of said soluble ionic salt.

9. The contractile apparatus as claimed in claim 1 further comprising a strain gauge to monitor a length of said polymer composite.

10. The contractile apparatus as claimed in claim 9 further comprising a controller for controlling the means for passing the first and second electrical current to said polymer composite based upon said length of said polymer composite.

11. The contractile apparatus as claimed in claim 1 further comprising a plurality of polymer composites and wherein said electrical conductor is in electrical communication with each of said plurality of polymer composites such that each of said polymer composites may be controlled substantially simultaneously.

12. A contractile apparatus comprising:

an electrical conductor;

a polymer composite in electrical communication with said conductor, said polymer composite comprising;

a nonionic polymer hydrogel containing a soluble ionic salt; and

an ionic polymer hydrogel in intimate contact with said nonionic polymer hydrogel;

a measuring device to measure the state of said polymer composite;

means for passing a first electric current of predetermined polarity passed through said electrical conductor to said polymer composite to cause said soluble salt in said nonionic polymer hydrogel to pass ions to said ionic polymer hydrogel resulting in a contraction of said ionic polymer hydrogel; and

means for passing a second electric current of predetermined and opposite polarity to the polarity of said first electric current through said electrical conductor to said polymer composite to cause said ions from said ionic polymer hydrogel to pass to said soluble salt in said nonionic polymer hydrogel resulting in a relaxation of said ionic polymer hydrogel;

wherein both of said means result in two-way migration of said ions in said polymer composite.

13. The contractile apparatus as claimed in claim 12 further comprising a controller for controlling the means for passing the first and second electrical current to said polymer composite based upon said state of said polymer composite.

14. The contractile apparatus as claimed in claim 13 further comprising a second ionic polymer hydrogel in intimate contact with said nonionic polymer hydrogel.

15. The contractile apparatus as claimed in claim 14 wherein said ionic polymer hydrogel is a cationic polymer hydrogel and wherein said second polymer hydrogel is an anionic polymer hydrogel.

16. The contractile apparatus as claimed in claim 15 wherein said soluble salt comprises a cation producing salt and an anion producing salt.

17. The contractile apparatus as claimed in claim 13 wherein said polymer composite is formed into a substantially cylindrical rod comprising a conductive core, a layer of said nonionic polymer hydrogel disposed about said core, a layer of said ionic polymer hydrogel disposed about said layer of nonionic polymer hydrogel, and a conductive coating disposed about said layer of ionic polymer hydrogel.

18. The contractile apparatus as claimed in claim 17 further comprising a second layer of ionic polymer hydrogel disposed between said conductive core and said nonionic polymer hydrogel and wherein one ionic polymer hydrogel is a cationic polymer hydrogel and another ionic polymer hydrogel is an anionic polymer hydrogel.

19. The contractile apparatus as claimed in claim 13 wherein said measuring device is a calorimetric device to monitor a concentration of said soluble ionic salt and wherein said controller controls the means for passing the first and second electrical current to said polymer composite based upon said concentration of said soluble ionic salt.

20. The contractile apparatus as claimed in claim 13 wherein said measuring device is a strain gauge to monitor a length of said polymer composite and wherein said controller controls the means for passing the first and second electrical current to said polymer composite based upon said length of said polymer composite.