Plasmonic nanohole arrays on hybrid substrate for highly sensitive label-free biosensing

1. A biosensor system comprising:

a microfluidic channel; and

a biosensor device located in the microfluidic channel, wherein the biosensor device includes,

a metal layer;

a transparent substrate layer; and

a dielectric layer;

wherein the metal layer includes a plurality of sub-wavelength apertures,

wherein the dielectric layer is located between the metal layer and the transparent substrate layer to form a spectrally isolated and well-defined optical transmission resonance through the extraordinary optical transmission (EOT) phenomenon, and wherein the biosensor device is configured for optical label-free biodetection of at least one substance in a sample based on refractive index sensing when the sample is introduced into the microfluidic channel so as to contact the biosensor device.

2. The biosensor system according to claim 1 , wherein the dielectric layer has a refractive index value higher than the substrate layer.

3. The biosensor system according to claim 1 , wherein the dielectric layer has a thickness between 70 nm and 250 nm.

4. The biosensor system according to claim 1 , wherein a diameter of each one of the sub-wavelength apertures is between 100 nm and 220 nm.

5. The biosensor system according to claim 1 , wherein a refractive index of the dielectric layer is more than 2.

6. The biosensor system according to claim 1 , wherein the dielectric layer of the biosensor device includes silicon nitride.

7. The biosensor system according to claim 1 , further comprising:

a spectrometer configured to measure an optical transmission spectrum of a substance to be identified in the microfluidic channel and to integrate spectral information of the optical transmission spectrum in a predetermined wavelength range to improve a detection limit.

8. A method for carrying out bio-sensing, the method comprising the steps of:

providing a biosensor device in a microfluidic channel, the biosensor device including a metal layer, a transparent substrate layer, and a dielectric layer, the metal layer having a plurality of sub-wavelength apertures, and the dielectric layer located between the metal layer and the transparent substrate layer to form a spectrally isolated and well-defined optical transmission resonance through the extraordinary optical transmission (EOT) phenomenon;

introducing a sample containing at least one substance to be identified into the microfluidic channel so that the at least one substance contacts the plurality of sub-wavelength apertures of the metal layer;

measuring an optical transmission spectrum of the least one substance to be identified; and

performing optical label-free biodetection of the at least one substance based on refractive index sensing.

9. The method according to claim 8 , further comprising the step of:

monitoring changes of a resonance wavelength of the optical transmission spectrum.

10. The method according to claim 8 , further comprising the step of:

integrating spectral information of the optical transmission spectrum in a predetermined wavelength range to improve a detection limit.

11. The method according to claim 8 , wherein the dielectric layer has a refractive index value higher than the substrate layer.

12. The method according to claim 8 , wherein the dielectric layer has a thickness between 70 nm and 250 nm.

13. The method according to claim 8 , wherein a diameter of each one of the sub-wavelength apertures is between 100 nm and 220 nm.

14. The method according to claim 8 , wherein a refractive index of the dielectric layer is more than 2.

15. The method according to claim 8 , wherein the dielectric layer of the biosensor device includes silicon nitride.