# US 2012/0075634 A1 · Sensor, Method for Detecting The Presence and/or Concentration of an Analyte Using the Sensor, and Use of the Method

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- Number: US 2012/0075634 A1
- Document ID: US20120075634A1
- Status: Published application
- Kind: A1
- Application number: 13/239,023
- Filed: 2011-09-21
- Published: 2012-03-29
- Earliest claimed: 2010-09-27
- Assignees: Stichting IMEC Nederland
- Inventors: Ling Sieben-Xu; Peter Offermans; Devrez Mehmet Karabacak; Mercedes Crego Calama; Sywert Brongersma
- Web page: https://patentgrep.com/patent/US20120075634A1

## CPC

- G01N 21/553: {and using surface plasmons (fluorescence excitation G01N21/648; enhanced Raman G01N21/658)}
- G01N 21/554: {detecting the surface plasmon resonance of nanostructured metals, e.g. localised surface plasmon resonance}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Methods and sensors for detecting the presence and/or concentration of an analyte are disclosed. In one aspect, a sensing element for use in a sensor is disclosed. The sensing element comprises a resonant cavity device configured to emit optical radiation at an initial power level, a sensing layer exhibiting an initial refractive index, and a detector. The sensing layer is configured to absorb or adsorb an analyte and, in response to absorbing or adsorbing the analyte, exhibit a modified refractive index that differs from the initial refractive index. The resonant cavity device is further configured to, in response to the sensing layer absorbing or adsorbing the analyte, emit optical radiation at a modified power level based on the modified refractive index. The detector is configured to detect the modified power level.

## Claims

### Claim 1

A sensing element comprising:
a resonant cavity device configured to emit optical radiation at an initial power level;
a sensing layer exhibiting an initial refractive index; and
a detector, wherein:
the sensing layer is configured to absorb or adsorb an analyte and, in response to absorbing or adsorbing the analyte, exhibit a modified refractive index that differs from the initial refractive index;
the resonant cavity device is further configured to, in response to the sensing layer absorbing or adsorbing the analyte, emit optical radiation at a modified power level based on the modified refractive index; and
the detector is configured to detect the modified power level.

### Claim 2 (depends on 1)

The sensing element of claim 1, wherein the resonant cavity device comprises:
a first mirror on a first side of the resonant cavity device, wherein the first mirror is configured to emit the optical radiation; and
a second mirror on a second side opposite the first side, wherein the second mirror exhibits an initial reflectivity.

### Claim 3 (depends on 2)

The sensing element of claim 2, wherein, in response to the sensing layer absorbing or adsorbing the analyte, the second mirror exhibits a modified reflectivity that is lower than the initial reflectivity.

### Claim 4 (depends on 3)

The sensor of claim 3, wherein the modified reflectivity is less than about 97%.

### Claim 5 (depends on 2)

The sensor of claim 2, wherein the second mirror comprises a structured layer.

### Claim 6 (depends on 5)

The sensor of claim 5, wherein the structured layer comprises a structured metal layer.

### Claim 7 (depends on 5)

The sensor of claim 5, wherein the structured layer comprises at least one of a metal grating, a metal nanohole array, and a metal nanoparticle array.

### Claim 8 (depends on 2)

The sensor of claim 2, wherein at least one of the first mirror and the second mirror comprises a distributed Bragg reflector (DBR) mirror.

### Claim 9 (depends on 8)

The sensor of claim 8, wherein the second mirror comprises a DBR mirror integrated with the structured layer.

### Claim 10 (depends on 8)

The sensor of claim 8, wherein the second mirror comprises a number of periods of a DBR mirror.

### Claim 11 (depends on 8)

The sensor of claim 8, wherein the DBR mirror comprise a dielectric DBR mirror.

### Claim 12 (depends on 1)

The sensor of claim 1, wherein the detector comprises a photodetector.

### Claim 13 (depends on 1)

The sensor of claim 1, wherein the resonant cavity device comprises a vertical cavity surface emitting laser.

### Claim 14 (depends on 1)

The sensor of claim 1, wherein the sensing layer comprises at least one of bio-molecules, polymers, and binding-DNA.

### Claim 15 (depends on 1)

The sensor of claim 1, wherein the initial reflectivity is greater than about 99% in a predetermined wavelength range.

### Claim 16

A method comprising:
using a first mirror in a resonant cavity device in a sensing element to emit optical radiation at an initial power level;
exposing a sensing layer in the sensing element to an analyte, thereby reducing a reflectivity of a second mirror in the resonant cavity device;
in response to reducing the reflectivity of the sensing layer, using the first mirror of the resonant cavity device to emit optical radiation at a modified power level; and
using a detector in the sensing element to detect the modified power level.

### Claim 17 (depends on 16)

The method of claim 16, further comprising:
in response to exposing the sensing layer to the analyte, exciting a surface plasmon resonance between the sensing layer and the second mirror, thereby reducing the reflectivity of the second mirror.

### Claim 18 (depends on 16)

The method of claim 16, wherein in response to reducing the reflectivity of the sensing layer, the resonant cavity device exhibits a modified carrier density, thereby causing a change in a junction voltage of the resonant cavity device, the method further comprising:
using the detector to detect the change in the junction voltage.

### Claim 19

A sensor comprising:
a number of sensing elements, each sensing element comprising:
a resonant cavity device configured to emit optical radiation at an initial power level;
a sensing layer exhibiting an initial refractive index; and
a detector, wherein:
the sensing layer is configured to absorb or adsorb an analyte and, in response to absorbing or adsorbing the analyte, exhibit a modified refractive index that differs from the initial refractive index;
the resonant cavity device is further configured to, in response to the sensing layer absorbing or adsorbing the analyte, emit optical radiation at a modified power level based on the modified refractive index; and
the detector is configured to detect the modified power level.

### Claim 20 (depends on 19)

The sensor of claim 19, wherein the number of sensing elements comprise an array of sensing elements.