Injection compression molding of transmission-type Fano resonance biochips for multiplex sensing applications

Abstract Nanostructure-based surface plasmon resonance biosensors have attracted considerable attention since the phenomenon of extraordinary light transmission in metallic nanohole arrays was discovered. However, the mass production of uniform metallic nanostructures with a low-cost, rapid, and high-throughput fabrication process remains a key issue for various multiplex sensing applications. We successfully utilized injection compression molding to mass fabricate transmission-type Fano resonance biochips with a feature size of 60 nm for multiplex sensing applications. Two types of metallic nanostructures, aluminum nanoslits and capped aluminum nanoslits with 24 sensing arrays, were made on polycarbonate substrates. The bulk sensitivity and uniformity of the nanostructure arrays were tested. A Fano resonance with a full-width at half-maximum bandwidth of 8 nm was observed in the visible light region for 470-nm-period capped aluminum nanoslit arrays. The refractive index sensitivity was 460 nm/RIU, and a figure of merit of 58 was achieved. Moreover, aluminum nanoslits had a dip resonance with a bandwidth of 25 nm and a refractive index sensitivity of 463 nm/RIU. The coefficients of variation of the refractive index sensitivities for 24 arrays on a biochip and 10 biochips from different fabrication batches were both below 3%, which indicates that uniform nanostructures can be fabricated by injection compression molding and that the reproducibility is controllable. In addition, the multiplex sensing capability of the aluminum nanostructure arrays was demonstrated by simultaneously monitoring 24 water/glycerin solutions with a hyperspectral imaging system. Protein–protein interactions between bovine serum albumin and anti-bovine serum albumin demonstrated proof of concept of the biological detection capability of the chips. To benefit various multiplex sensing applications such as clinical disease diagnosis, drug screening, and protein biomarker discovery, 96-array aluminum nanoslit biochips the same size as a standard 96-well plate were successfully fabricated. Such a nanostructure-based plasmonic biochip produced by a low-cost, rapid, and high-throughput fabrication method can benefit commercial applications.