**6. Design, simulations and potential applications**

We present in this section the design, simulation results and potential futuristic on-chip applications of our device.

## **6.1 Software simulation and design**

To model how the evanescent waves would couple with bio-species in a cavity etched in the nitrite layer as light waves travel through the waveguide, we performed optical simulations using RSoft BeamProp optical simulation software. As represented in **Figure 11**, light emitted from the optical source travels through the waveguide. As the resultant evanescent wave travels through the cavity etched deep into the nitride layer, it is exposed to specific analyte material trapped within the cavity. In this design, a multimode wave travels through high refractive index bridge waveguide and interacts with material within the etched cavity in the nitride layer. The interaction, in this case, would be primarily a function of the specific refractive index of the analyte inside that cavity, since the multimode light traveling in the waveguide will interact and be diverted into the absorbed analyte. The unique fingerprints of each material within the cavity then produces a change in signal that is recognizable by the detector, as in **Figure 11(a)**.

#### **6.2 Applications in futuristic micro- and nano-dimensioned devices**

Applications already proposed and demonstrated for Si Av LEDs include micro displays [44, 45] and Lab-on-chip systems [46, 47]. Analyses of test results from our device open up exciting possibilities for potential applications for the derived technology in futuristic integrated on-chip optoelectronic and biosensor applications.

These applications can be achieved through (1) placements of specific designed optical sources with specific directional and dispersive emission characteristics; (2) design and placement of micro wavelength dispersive coupling into micro dimensioned on-chip optical waveguides, and (3) design and placement of broadband wavelength emitters for diverse on-chip electro-optic applications. Other possible applications include (4) realization of various on-chip nano- and micro-dimensioned sensors that can detect a variety of parameters, ranging from standard physical parameters to a range of derived bio-parameters through the

#### **Figure 11.**

*Bridge waveguide design realization with RSoft BeamProp optical simulation software: (a) design of bridge waveguide device [43], (b) optical simulation run for the bridge waveguide.*

*Nanomaterial-Enhanced Receptor Technology for Silicon On-Chip Biosensing Application DOI: http://dx.doi.org/10.5772/intechopen.94249*

**Figure 12.**

*Application of optical biosensor based on evanescent wave interaction and nanomaterial enhancement for increased sensitivity and selectivity of target analytes in the within the cavity in the interaction area.*

use of waveguide optics and intermediate evanescent-based waveguide receptor layers. An attractive feature of these applications is the micro-positioning of the optical source itself through micro- and nano-lithographic technology, the design of waveguides and wavelength dispersers using the same technology, and the design of micro-electronic processing technology in close proximity to the optical source and detectors to process and transfer derived information to adjacent on-chip processing circuitry. **Figure 12** demonstrates a typical application where the AgNPs synthesized are deployed in the etched cavity within the nitrite layer to form a highly sensitive platform for selective detection of analytes like prostate specific antigen, which is a biomarker for prostate cancer cells.
