| abstract |
An optical sensor and method are disclosed for use with a visible-light laser excitation beam (60) and a Raman spectroscopy detector, for detecting the presence chemical groups in an analyte (80) applied to the sensor. The sensor includes a substrate (10), a plasmon resonance mirror (20) formed on a sensor surface of the substrate (10), a plasmon resonance particle layer (40) disposed over the mirror (20), and an optically transparent dielectric layer (30) about 2-40 nm thick separating the mirror (20) and particle layer (40). The particle layer (40) has a periodic array of plasmon resonance particles with (i) a coating to binding analyte molecules (80), (ii) substantially uniform particle sizes and shapes in a range between 50-200 nm (ii) a particle-to-particle spacing less than the wavelength of the laser excitation beam. The device is capable of detecting single analyte molecules (80) with an amplification factor of up to 1012 1014. |