Chemical impedance detectors for fluid analyzers
A chemical impedance detector having several electrodes situated on or across a dielectric layer of a substrate. The electrodes may be across or covered with a thin film polymer. Each electrode may have a set of finger-like electrodes. Each set of finger-like electrodes may be intermeshed, but not in contact, with another set of finger-like electrodes. The thin-film polymer may have a low dielectric constant and a high porous surface area. The chemical impedance detector may be incorporated in a micro fluid analyzer system.
1. An impedance detector comprising:
a substrate;
a dielectric layer situated on the substrate;
a first electrode situated on the dielectric layer;
a second electrode situated on the dielectric layer; and
a polymer layer situated on a portion of the first electrode, a portion of the second electrode, and an area of the dielectric layer between the first electrode and the second electrode; and
wherein:
the first and second electrodes are interdigitated electrodes having a height;
the polymer layer is a low dielectric, porous, high surface area thin-film; and
the polymer layer disposed between the first electrode and the second electrode has a thickness approximately equal to the height of the first or second electrodes.
2. The detector of claim 1 , wherein:
the first electrode comprises a first plurality of finger-like electrodes;
the second electrode comprises a second plurality of finger-like electrodes; and
wherein the first plurality of finger-like electrodes is intermeshed, but not in contact, with the second plurality of finger-like electrodes.
3. The detector of claim 2 , wherein the electrodes comprise a porous structure.
4. The detector of claim 3 , wherein the electrodes are low-height and low-width electrodes.
5. The detector of claim 1 , wherein:
the substrate is silicon;
the dielectric layer is SiO 2 ;
the electrodes comprise conductive material; and
the polymer layer is a material having a low dielectric constant, porosity, and/or a high partition coefficient for a target analyte.
6. An impedance detector system, comprising:
a first interdigitated chemical impedance detector comprising:
a substrate;
a dielectric layer situated on the substrate;
a first electrode situated on the dielectric layer;
a second electrode situated on the dielectric layer; and
a continuous polymer layer situated on the first electrode, the second electrode, and an area on the dielectric layer between the first and second electrodes, the polymer layer comprising a porous, high surface area thin-film; and
wherein the polymer layer disposed between the first electrode and the second electrode has a thickness approximately equal to a height of the first or second electrodes; and
a second interdigitated chemical impedance detector comprising:
a substrate;
a dielectric layer situated on the substrate;
a first electrode situated on the dielectric layer;
a second electrode situated on the dielectric layer; and
a continuous polymer layer situated on the first electrode, the second electrode, and an area on the dielectric layer between the first and second electrodes, the polymer layer comprising a porous, high surface area thin-film; and
wherein the polymer layer disposed between the first electrode and the second electrode has a thickness approximately equal to a height of the first and second electrodes.
7. The system of claim 6 , wherein the first and second chemical impedance detectors are connected in a differential mode.
8. The system of claim 7 , wherein:
the first chemical impedance detector is exposable to an analyte; and
the second impedance detector is exposable to a reference sample, which may contain a different concentration of the analyte.
9. The system of claim 7 , wherein the differential mode is an AC-coupled mode.
10. The system of claim 6 , wherein:
the first electrode of the first chemical impedance detector comprises a first plurality of finger-like electrodes;
the second electrode of the first chemical impedance detector comprises a second plurality of finger-like electrodes;
the first electrode of the second impedance detector comprises a third plurality of finger-like electrodes;
the second electrode of the second chemical impedance detector comprises a fourth plurality of finger-like electrodes;
the first plurality of finger-like electrodes is intermeshed, but not in contact, with the second plurality of finger-like electrodes; and
the third plurality of finger-like electrodes is intermeshed, but not in contact, with the fourth plurality of finger-like electrodes.
11. The detector of claim 10 , wherein:
the polymer layer has a low dielectric constant;
the electrodes are low-height and low-width electrodes; and
the electrodes are porous.
12. The system of claim 6 , further comprising:
an array of chemical impedance detectors; and
wherein:
the first and second chemical impedance detectors are in the array of chemical impedance detectors; and
each chemical impedance detector comprises:
a substrate;
a dielectric layer situated on the substrate;
a first electrode situated on the dielectric layer;
a second electrode situated on the dielectric layer; and
a polymer situated on the first electrode, the second electrode, and an area on the dielectric layer between the first and second electrodes.
13. The system of claim 12 , wherein:
the first electrode situated on the dielectric layer comprises a first plurality of low-height and low-width electrodes;
the second electrode of the chemical impedance detector comprises a second plurality of low-height and low-width electrodes; and
the first plurality of low-height and low-width electrodes is intermeshed, but not in contact, with the second plurality of low-height and low-width electrodes.