This paper presents a number of plasmonics based nanosensors that is currently being investigated in IHPC. In the first case, the influence of external magnetic field and electron on the field distribution of active semiconductor microcavity with elliptical shape is studied. It is observed that high amount of electron pumped into the elliptical microcavity demonstrate the plasmonics field distribution, which can be used to sense the change in wavelength and electron/holes densities. The second case will discuss about using plasmonics to enhance the electromagnetic wave from metallic waveguide slot. The enhancement is more than 100 times and this is important for the generation of electron-holes pair in PIN based photo-detector. The third case will discuss using the metallic nanowire to sense different surrounding materials. The small differences in the refractive index of the surrounding materials show the different plasmonics resonance frequencies.