Physiological characteristic sensors and methods for forming such sensors

• US 10,845,330 B2
• Filed: 05/15/2017
• Issued: 11/24/2020
• Est. Priority Date: 05/01/2014
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Jacks, Steven C., Gautham, Raghavendhar, Liang, Bradley C., Little, Megan E., Pesantez, Daniel E., Shah, Rajiv
• Primary Examiner(s): Cohen, Brian W
• Application Number:
  US15/595,687
• Publication Number:
  US 20170248542A1
• Time in Patent Office: 1,289 Days
• 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, wherein the pulsed signal includes a repeated cycle of a first current and a second current different from the first current, and applying a non-pulsed continuous signal to the sensor electrode, wherein the non-pulsed continuous signal includes a non-repeated application of a third current, 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, wherein the pulsed signal includes a repeated cycle of a first current and a second current different from the first current, wherein the first current and the second current have a same polarity, and applying a non-pulsed continuous signal to the sensor electrode, wherein the non-pulsed continuous signal includes a non-repeated application of a third current, to form a platinum deposit on the sensor electrode.

2. 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.

3. 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.

4. The method of claim 1 wherein applying the pulsed signal to the sensor electrode comprises applying the repeated cycle of the first current of between about −

50 μ

A and about −

150 μ

A and the second current of less than 0 μ

A and about −

20 μ

A.

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

6. 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 the first current and about 0.1 seconds to about 4 seconds of the second current to the sensor electrode.

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

8. 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).

9. The method of claim 1 wherein applying the 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.

10. The method of claim 1 wherein applying the 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 the 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.

11. The method of claim 1, wherein the electrodeposition process forms the sensor electrode with an electrochemical real surface area at least about 80 times greater than a cross sectional area of the sensor electrode.

12. The method of claim 11, wherein the sensor electrode is formed with 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.

18. The method of claim 1 wherein the first current and the second current each have a negative polarity.

13. 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, wherein the pulsed signal includes a repeated cycle of a first current and a second current different from the first current, wherein the first current and the second current have a same polarity, and applying a non-pulsed continuous signal to the deposition site, wherein the non-pulsed continuous signal includes a non-repeated application of a third current, to form the platinum deposit on the deposition site.

14. The method of claim 13 wherein applying the pulsed signal to the deposition site comprises applying cycles of about 0.1 seconds to about 4 seconds of the first current and about 0.1 seconds to about 4 seconds of the second current to the deposition site, and wherein applying the non-pulsed continuous signal to the deposition site comprises applying the third current to the deposition site for from about 50 seconds to about 240 seconds.

15. The method of claim 13 wherein performing the hybrid pulse/continuous electrodeposition process further comprises applying a second pulsed signal to the deposition site, wherein the second pulsed signal includes a repeated cycle of a fourth current and a fifth current different from the fourth current.

16. The method of claim 13, wherein the hybrid pulse/continuous electrodeposition process forms the platinum deposit with an electrochemical real surface area at least about 80 times greater than a cross sectional area of the platinum deposit.

17. The method of claim 16, wherein the hybrid pulse/continuous electrodeposition process forms the platinum deposit with 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.

19. The method of claim 13 wherein the first current and the second current each have a negative polarity.

20. The method of claim 19 wherein applying the pulsed signal to the deposition site comprises applying the repeated cycle of the first current of between about −

50 μ

A and about −

150 μ

A and the second current of less than 0 μ

A and about −

20 μ

A.