Sensors, methods of making and devices
Disclosed sensors can include at least one resonator (in some embodiments, at least two resonators) and various other structures that may be formed in association with the resonators. The at least one resonator in embodiments can include a bottom electrode, a piezoelectric layer, and a top electrode, wherein the piezoelectric layer is positioned between the bottom electrode and the top electrode.
1 . A method of forming a sensor, comprising:
forming a first acoustic resonator, the first resonator comprising a first surface and an opposing second surface, and wherein the first resonator comprises:
a bottom electrode;
a piezoelectric layer on at least a portion of the bottom electrode; and
a top electrode on at least a portion of the piezoelectric layer; and
depositing a metal oxide layer on the second surface of the first resonator, and forming a coupling layer comprising silane on the metal oxide layer;
depositing a molecular recognition component on the coupling layer;
forming a second acoustic resonator aligned with the first resonator; and
positioning a Bragg reflector stack beneath the first and second resonators, and connecting the first and second resonators in series to diminish parasitic resonances of the Bragg reflector stack.
2 . The method according to claim 1 , further comprising depositing a reference binding material on the second resonator, wherein:
the reference binding material is adapted to calibrate the sensor, and is a different material than the molecular recognition component;
the molecular recognition component is selected to bind with a target analyte; and
the reference binding material is selected to avoid binding with the target analyte.
3 . The method according to claim 2 , further comprising depositing the reference binding material above the metal oxide layer and coupling layer.
4 . The method according to claim 2 , wherein the thickness of the metal oxide layer is between 10 A and 50 A.
5 . The method according to claim 2 , further comprising:
providing a first surface and an opposing second surface at the second resonator, and wherein the second resonator comprises:
a bottom electrode;
a piezoelectric layer on at least a portion of the bottom electrode; and
a top electrode on at least a portion of the piezoelectric layer; and
depositing the metal oxide layer on at least the second surface of at least the first resonator and the second surface of the second resonator, wherein the metal oxide layer is deposited using atomic layer deposition (ALD); and
depositing the reference binding material on the silane layer at the second resonator.
6 . The method according to claim 2 , wherein the reference binding material comprises a molecule having a molecular weight substantially similar to that of the molecular recognition component.
7 . The method according to claim 1 , wherein the coupling layer comprises an epoxy silane layer bound to the metal oxide layer.
8 . The method according to claim 1 , further comprising dicing a wafer on which a plurality of sensors have been formed.
9 . The method according to claim 2 , wherein the molecular recognition component layer and the reference binding material layer each have a substantially circular shape.
10 . The method according to claim 5 , further comprising positioning the Bragg reflector stack under the bottom electrode of the first resonator and the bottom electrode of the second resonator.
11 . The method according to claim 4 , wherein the metal oxide layer comprises TiO 2 .