PHYSIOLOGICAL CHARACTERISTIC SENSORS AND METHODS FOR FORMING SUCH SENSORS

• US 20150316499A1
• Filed: 05/01/2014
• Published: 11/05/2015
• Est. Priority Date: 05/01/2014
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Gautham, Raghavendhar, Liang, Bradley C., Little, Megan E., Pesantez, Daniel E., Shah, Rajiv, Jacks, Steven C.
• Granted Patent: US 9,681,828 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 2562/125 characterised by the manufacture of electrodes
• CPC Class Codes: A61B 5/1451 for interstitial fluid
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: C23C 28/00 Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
• CPC Class Codes: C25D 3/52 characterised by the organic bath constituents used
• CPC Class Codes: C25D 3/567 containing more than 50% by weight of platinum group metals
• CPC Class Codes: C25D 5/18 Electroplating using modulated, pulsed or reversing current
• CPC Class Codes: C25D 5/605 Surface topography of the layers, e.g. rough, dendritic or nodular layers
• CPC Class Codes: C25D 7/00 Electroplating characterised by the article coated
• CPC Class Codes: G01N 27/30 Electrodes, e.g. test electrodes; Half-cells G01N27/414 takes precedence
• CPC Class Codes: G01N 27/327 Biochemical electrodes , e.g. electrical or mechanical details for in vitro measurements
• CPC Class Codes: G01N 27/416 Systems G01N27/27 takes precedence

Abstract

A physiological characteristic sensor, a method for forming a physiological characteristic sensor, and a method for forming a platinum deposit having a rough surface are presented here. The method for forming a physiological characteristic sensor includes immersing a sensor electrode in a platinum electrolytic bath. Further, the method includes performing an electrodeposition process by sequentially applying a pulsed signal to the sensor electrode and applying a non-pulsed continuous signal to the sensor electrode to form a platinum deposit on the sensor electrode.

Claims

1. A method for forming a physiological characteristic sensor, the method comprising the steps of:

immersing a sensor electrode in a platinum electrolytic bath; and

performing an electrodeposition process by sequentially applying a pulsed signal to the sensor electrode and applying a non-pulsed continuous signal to the sensor electrode to form a platinum deposit on the sensor electrode.

2. The method of claim 1 further comprising:

providing a base layer;

forming an adhesion layer over the base layer;

forming a metallization layer over the adhesion layer; and

patterning an insulation layer over the metallization layer to define a selectively exposed surface of the metallization layer, wherein the selectively exposed surface of the metallization layer forms the sensor electrode.

3. The method of claim 1 wherein the sensor electrode has an initial surface area, and wherein performing the electrodeposition process comprises forming a modified electrochemical real surface area at least 80 times greater than the initial surface area.

4. The method of claim 1 wherein performing the electrodeposition process comprises applying the pulsed signal to the sensor electrode before applying the non-pulsed continuous signal to the sensor electrode.

5. The method of claim 1 wherein performing the electrodeposition process comprises applying the pulsed signal to the sensor electrode after applying the non-pulsed continuous signal to the sensor electrode.

6. The method of claim 1 wherein applying the pulsed signal to the sensor electrode comprises applying cycles of a first current of from about −

50 μ

A to about −

150 μ

A and a second current of from about 0 μ

A to about −

20 μ

A.

7. The method of claim 1 wherein applying the pulsed signal to the sensor electrode comprises applying from about 100 to about 300 cycles of a first current and a second current to the sensor electrode.

8. The method of claim 1 wherein applying the pulsed signal to the sensor electrode comprises applying cycles of about 0.1 seconds to about 4 seconds of a first current and about 0.1 seconds to about 4 seconds of a second current to the sensor electrode.

9. The method of claim 1 wherein applying the pulsed signal to the sensor electrode comprises applying a pulsed current in a square pulse pattern.

10. The method of claim 1 wherein applying the non-pulsed continuous signal to the sensor electrode comprises applying a non-pulsed continuous current of from about −

50 μ

A to about −

120 μ

A to the sensor electrode for from about 50 seconds to about 240 seconds.

11. The method of claim 1, wherein immersing the sensor electrode in a platinum electrolytic bath comprises immersing the sensor electrode in a solution of hydrogen hexachloroplatinate (H₂PtCl₆) and lead acetate trihydrate (Pb(CH₃COO)₂.3H₂O).

12. The method of claim 1 wherein applying a pulsed signal to the sensor electrode comprises applying a first pulsed signal to the sensor electrode in a first sequence and applying a second pulsed signal to the sensor electrode in a second sequence.

13. The method of claim 1 wherein applying a pulsed signal to the sensor electrode comprises:

applying a first pulsed current to the sensor electrode in a first sequence by applying cycles of a first current of from about −

80 μ

A to about −

120 μ

A and a second current of from about 0 μ

A to about −

10 μ

A;

applying a second pulsed current to the sensor electrode in a second sequence by applying cycles of a third current of from about −

80 μ

A to about −

100 μ

A and a fourth current of from about −

70 μ

A to about −

90 μ

A; and

applying a non-pulsed continuous current of from about −

70 μ

A to about −

110 μ

A.

14. The method of claim 1 wherein applying a pulsed signal to the sensor electrode comprises applying a first pulsed signal to the sensor electrode in a first sequence and applying a second pulsed signal to the sensor electrode in a second sequence and wherein applying a non-pulsed continuous signal to the sensor electrode comprises applying a first non-pulsed continuous signal to the sensor electrode and applying a second non-pulsed continuous signal to the sensor electrode.

15. The method of claim 1 wherein performing the electrodeposition process comprises:

applying a pulsed signal to the sensor electrode;

applying a first step signal to the sensor electrode;

applying a second step signal to the sensor electrode;

applying a third step signal to the sensor electrode;

applying a fourth step signal to the sensor electrode; and

applying the non-pulsed continuous signal to the sensor electrode.

16. A method for forming a platinum deposit having a rough surface, the method comprising the steps of:

contacting a deposition site with a platinum electrolyte; and

performing a hybrid pulse/continuous electrodeposition process by sequentially applying a pulsed signal to the deposition site and applying a non-pulsed continuous signal to the deposition site to form the platinum deposit on the deposition site.

17. The method of claim 16 wherein performing the hybrid pulse/continuous electrodeposition process comprises applying the pulsed signal to the deposition site before applying the non-pulsed continuous signal to the deposition site.

18. The method of claim 16 wherein performing a hybrid pulse/continuous electrodeposition process comprises sequentially applying a first pulsed signal to the deposition site and applying a second pulsed signal to the deposition site.

19. A physiological characteristic sensor comprising:

a sensor base;

an electrode located on the sensor base, the electrode having a cross sectional area and an electrochemical real surface area at least about 80 times greater than the cross sectional area;

a semipermeable membrane selective to an analyte positioned over the electrode;

a reagent encapsulated between the semipermeable membrane and the electrode;

a protein layer encapsulated between the semipermeable membrane and the electrode; and

an adhesion promoter layer between the protein layer and the semipermeable membrane.

20. The physiological characteristic sensor of claim 19 wherein the electrode includes a platinum coating having the cross sectional area and the electrochemical real surface area, wherein the platinum coating includes a substantially continuous base portion having a thickness of from about 0.5 to about 1.5 μ

m and a discontinuous upper portion having thickness of from about 0.6 to about 2.5 μ

m.