Angle-resolved diffraction grating biosensor based on porous silicon

Abstract

In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

Asymmetric nanofluidic grating detector for differential refractive index measurement and biosensing

“…This principle has previously been used for displacement sensing in micromechanics, [11][12][13] for chemical sensing, [14][15][16][17] and for biosensing. [18][19][20] In chemical and biological sensing, many powerful device concepts have been proposed based on micropatterning capture molecules or hydrogels into stimulus-responsive phase gratings. 18,21 Binding of target molecules or swelling of the hydrogel alters the wavefront of a laser passing through the element, and this can be read out via a consequent change of the diffraction pattern in the farfield.…”

Multi-step proportional miniaturization to sub-micron dimensions using pre-stressed polymer films

“…Starting from 15 mm features of the master, patterns as small as 750 nm were fabricated. We applied this new capability to fabricate patterns in a silicon wafer that can be used as a functional substrate for many applications such as diffraction grating based sensors 14,15 or as a master template for so lithography applications. 16,17…”

Photofunctionalizable Hydrogel for Fabricating Volume Optical Diffractive Sensors

“…Optical grating sensors have been reported for measuring a variety of analytes including pH, lead ions, thrombin, and viruses . The basic principle of operation of the grating sensors is the modulation of the intensity of light transmitted in a specified direction as a result of a change in the geometrical dimensions, absorption, and/ or refractive index of the alternating strips caused by analytes . The specificity is achieved by incorporating analyte‐sensitive moieties (or ligands) in the material used to make the alternating strips of the gratings.…”

“…Amplitude grating sensors are commonly fabricated using soft lithography where a precursor solution of the hydrogel with absorbing analyte‐sensitive indicator is patterned using an elastomer stamp 5b,8. Alternatively, a continuous film of photosensitive hydrogel is spatially patterned by selective photodegradation using light .…”