Realizing micro- and nano-optical bio sensors on chip

Si LEDs that operate in the reverse avalanche mode (Si AM LED) and forward bias (Si FB LED), offer various possibilities for realizing nano and micro biosensors directly on chip. The LEDs operate in 450 - 1100nm wavelength range, can emit up to 100nW of optical power, and can be fabricated in micro and nano dimensions. The dispersion characteristics has been studied for a Si AM LED source that is positioned one micron below silicon surface. Subsequently, a fluidic channel sensor device has been designed using the dispersion characteristics. Hence transmittance and absorption spectra studies of species that flow in a fluidic channel can be studied. Similarly, a waveguide-based sensor device has been designed where a receptor layer is fabricated on a waveguide on chip between a Si AM LED and a Si p-i-n detector. The receptor layer binds preferentially with a defined pathogen, and couples with the evanescent radiation of the waveguide.