Nanophotonic lab-on-a-chip platforms including novel bimodal interferometers, microfluidics and grating couplers

Abstract

One of the main limitations for achieving truly lab-on-a-chip (LOC) devices for point-of-care diagnosis is the incorporation of the "on-chip" detection. Indeed, most of the state-of-the-art LOC devices usually require complex read-out instrumentation, losing the main advantages of portability and simplicity. In this context, we present our last advances towards the achievement of a portable and label-free LOC platform with highly sensitive "on-chip" detection by using nanophotonic biosensors. Bimodal waveguide interferometers fabricated by standard silicon processes have been integrated with sub-micronic grating couplers for efficient light in-coupling, showing a phase resolution of 6.6 × 10(-4)× 2π rad and a limit of detection of 3.3 × 10(-7) refractive index unit (RIU) in bulk. A 3D network of SU-8 polymer microfluidics monolithically assembled at the wafer-level was included, ensuring perfect sealing and compact packaging. To overcome some of the drawbacks inherent to interferometric read-outs, a novel all-optical wavelength modulation system has been implemented, providing a linear response and a direct read-out of the phase variation. Sensitivity, specificity and reproducibility of the wavelength modulated BiMW sensor has been demonstrated through the label-free immunodetection of the human hormone hTSH at picomolar level using a reliable biofunctionalization process.

Direct and label‐free detection of the human growth hormone in urine by an ultrasensitive bimodal waveguide biosensor

“…At the end of the waveguide, the phase variation of the output light is directly related to the magnitude of the bio‐interaction. Our preliminary work related to the BiMW has already demonstrated its extremely high sensitivity for bulk changes of the refractive index and for surface sensing and the possibility of its integration in portable lab‐on‐a‐chip platforms .…”

Diagnosis of dengue: an update

“…These limitations may be due to the use of the lateral flow dipstick approach. The new lab-on-a-chip platform could offer a way to improve the performance of these bedside diagnostic tools [135][136][137]. This platform makes use of a number of new technologies; some in combination, such as microfluidics [135][136][137] and grating couplers [137] to improve multiplexing, accommodate better mixing of reagents with test samples as well as achieving greater sensitivity for detecting positive signals [138].…”

Surface modification of semiconducting silicon nanowires for biosensing applications

“…44,72 This can be explained because the product is expensive or needs to be chemically synthesized and/or leads to organic layers of poor quality. In fact, most of the time the carboxylic acid function is introduced via post-chemical modifi cation of a chemical group or functionality previously covalently grafted on SiNW, such as an ester, -NH 2 or vinyl species (see Section 3.4.2) allowing subsequent conjugation with amine-containing molecules.…”