Integrated ion sensing apparatus and methods
An integrated ion-sensitive probe is provided. In an example, an ion-sensitive probe can include a semiconductor substrate and a first passive electrode attached to the semiconductor substrate. The first passive electrode can be configured to contact a solution and to provide a first electrical voltage as function of a concentration of an ion within the solution. In certain examples, a passive reference electrode can be co-located on the semiconductor substrate. In some examples, processing electronics can be integrated on the semiconductor substrate.
1. An ion-sensitive probe to measure a concentration of an ion within a solution, the ion-sensitive probe comprising:
a semiconductor substrate;
a first passive electrode integrated with the semiconductor substrate and configured to contact the solution and to provide a first electrical voltage as a function of the concentration of the ion within the solution;
a second electrode integrated with the semiconductor substrate and configured to contact a reference solution, the second electrode in electrical contact with the first passive electrode; and
an amplifier integrated with the semiconductor substrate and having an input electrically coupled with the first passive electrode, wherein a location of the amplifier integrated within the semiconductor substrate is configured to provide a co-integrated transmission path of the first voltage to reduce susceptibility of interference of the first voltage between the first electrode and the input of the amplifier.
2. The probe of claim 1 , including a containment barrier for the reference solution, the containment barrier configured to maintain the reference solution in constant contact with the second electrode.
3. The probe of claim 2 , wherein the reference solution is a gel.
4. The probe of claim 1 , wherein the second electrode is a passive electrode.
5. The probe of claim 4 , wherein the reference solution includes a gel.
6. The probe of claim 4 , wherein the amplifier is electrically coupled to the first passive electrode and the second passive electrode.
7. The probe of claim 4 , wherein the first electrode includes a first sensing material configured to generate the electrical voltage when in contact with the solution; and
wherein the first sensing material includes iridium oxide configured to sense hydrogen ions.
8. The probe of claim 7 , wherein the second electrode includes
a containment barrier;
a first sensing material configured to generate the electrical voltage;
wherein the containment barrier is attached to the semiconductor substrate and forms a ring around a point of contact between the solution and the sensing material; and
wherein the containment barrier and the semiconductor substrate form at least a portion of a container for the reference solution.
9. The probe of claim 1 , wherein a diameter of a contact area of the first passive electrode is from 250 micrometers (um) to 1 millimeter (mm).
10. The probe of claim 1 , wherein the semiconductor substrate includes a first trace coupled to the first passive electrode, the trace configured to communicate the electrical voltage to sensing circuitry.
11. The probe of claim 10 , wherein the semiconductor substrate includes a shield trace surrounding the first passive electrode and the first trace, the shield trace configured to shield the electrical voltage from noise.
12. The probe of claim 1 , wherein a location of contact of the first passive electrode with the solution does not include a transistor configured to sense the ion.
13. The ion-sensitive probe of claim 1 , including:
a plurality of third passive electrodes; and
active electronics integrated with the semiconductor substrate, the active electronics configured to couple each of the plurality of third passive electrodes and the first passive electrode to the amplifier.
14. The ion-sensitive probe of claim 1 , including a wireless transmitter configured to wirelessly transmit a digital representation of an output of the amplifier.
15. the ion-sensitive probe of claim 14 , wherein the wireless transmitter is integrated with the semiconductor substrate.
16. A method for sensing an ion concentration of a solution, the method comprising:
contacting a sensing material of a first passive electrode with the solution, the first passive electrode integrated in a semiconductor substrate;
contacting a sensing material of a second electrode with a reference solution, the second electrode integrated in the semiconductor substrate;
generating a sensing voltage via a series connection of the first passive electrode and the second electrode, the sensing voltage indicative of the ion concentration of the solution;
amplifying a voltage of the first passive electrode and a voltage of the second passive electrode to provide the sensing voltage; and
wherein the amplifying a voltage of the first passive electrode and a voltage of the second passive electrode includes amplifying the voltage of the first passive electrode and the voltage of the second passive electrode using an amplifier circuit integrated with the semiconductor substrate, wherein a location of the amplifier integrated within the semiconductor substrate is configured to provide a co-integrated transmission path of the first voltage to reduce susceptibility of interference of the first voltage between the first electrode and the input of the amplifier.
17. The method of claim 16 , wherein contacting a sensing material of a second electrode includes contacting a sensing material of a second passive electrode with a reference solution.
18. The method of claim 16 , including communicating amplifier information from the ion-sensitive probe via a wireless transmitter.
19. The method of claim 16 , including coupling one passive indicating electrode of an plurality of passive indicating electrodes to the amplifier, the array of passive indicating electrodes including the first passive electrode.
20. An ion-sensitive probe to measure the concentration of an ion within a solution, the ion-sensitive probe comprising: a semiconductor substrate; and a first passive electrode integrated with the semiconductor substrate and configured to contact the solution; a second passive electrode, integrated with the same semiconductor substrate and configured to contact a reference solution having a specified concentration of the ion; an amplifier circuit, integrated with the same semiconductor substrate, and connected to the first and second passive electrodes, wherein the amplifier circuit is configured to provide a first electrical voltage as function of the concentration of the ion within the solution, wherein a location of the amplifier integrated within the semiconductor substrate is configured to provide a co-integrated transmission path of the first voltage to reduce susceptibility of interference of the first voltage between the first electrode and the input of the amplifier.