Physiological characteristic sensors and methods for forming such sensors

• US 9,681,828 B2
• Filed: 05/01/2014
• Issued: 06/20/2017
• Est. Priority Date: 05/01/2014
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Little, Megan E., Jacks, Steven C., Pesantez, Daniel E., Shah, Rajiv, Gautham, Raghavendhar, Liang, Bradley C.
• Primary Examiner(s): Ripa, Bryan D.
• Application Number:
  US14/267,739
• Publication Number:
  US 20150316499A1
• Time in Patent Office: 1,146 Days
• Field of Search: 205 95
• 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, 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, for from about 50 seconds to about 240 seconds to form a platinum deposit on the sensor electrode.

2. 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.

3. 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.

4. 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.

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

50 μ

A to about −

150 μ

A and the second current of from about 0 μ

A to about −

20 μ

A.

6. 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.

7. 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.

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

9. 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).

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.

11. The method of claim 1 wherein applying the 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; and

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

wherein applying the non-pulsed continuous signal to the sensor electrode comprises applying the non-pulsed continuous current of from about −

70 μ

A to about −

110 μ

A.

12. 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.

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

applying the 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.

14. 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, 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.

15. The method of claim 14 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.

16. The method of claim 14 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.

17. 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 including a repeated cycle of a first current and a second current different from the first current to the sensor electrode and applying a non-pulsed continuous signal including a non-repeated application of a non-pulsed continuous current to the sensor electrode to form a platinum deposit on the sensor electrode,

wherein applying the pulsed signal to the sensor electrode comprises;

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

80 μ

A to about −

120 μ

A and the second current of from about 0 μ

A to about −

10 μ

A; and

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

wherein applying the non-pulsed continuous signal to the sensor electrode comprises applying the non-pulsed continuous current of from about −

70 μ

A to about −

110 μ

A.

18. 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, 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, wherein performing the electrodeposition process comprises;

applying the 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.