Microfluidic-optical integrated CMOS compatible devices for label-free biochemical sensing

Abstract

The fabrication, characterization and packaging of novel microfluidic-optical integrated biosensors for label-free biochemical detection is presented in this paper. The integrated device consists of a three-dimensional embedded microchannel network fabricated using enhanced CMOS compatible SU-8 multilevel polymer technology on top of a wafer containing Mach-Zehnder Interferometer (MZI) nanophotonic biosensor devices. PMMA housing provides connection to the macro-world and ensures robust leakage-free flow operation of the devices. This macro-microfluidic module can operate at pressure drops up to 1000 kPa. Fluid flow experiments have been performed in order to demonstrate the robustness of our microfluidic devices. The devices have been designed to operate under continuous flow. Steady-state flow rates ranging from 1 to 100 µl min−1 at pressure drops ranging from 10 to 500 kPa were measured in the laminar flow regime. Experimental results are in good agreement with laminar flow theory. The first interferometric sensing measurements are presented in order to demonstrate the functionality of these novel integrated devices for lab-on-a-chip and label-free biosensing applications. A bulk refractive index detection limit of 3.8 × 10−6 was obtained, close to the minimum detected up to now by label-free biosensor devices without microfluidic integration. As far as we know, this is the first time that a label-free biosensor device is integrated within a microfluidic network using a wafer-level CMOS compatible process technology.

Experimental characterization of a silicon photonic biosensor consisting of two cascaded ring resonators based on the Vernier-effect and introduction of a curve fitting method for an improved detection limit

“…Slot waveguides with enhanced light-matter interaction have been applied to improve the sensitivity of ring resonator sensors with a factor two to four [8,9], but increased optical losses have prevented them so far from achieving better detection limits than normal ring resonator sensors. Integrated interferometers with large interaction lengths have also proved to be promising [10,11], with detection limits in the order of 10 −6 RIU. In [12] a sensor is introduced that consists of two cascaded ring resonators, and it is shown theoretically that it can obtain very high sensitivities thanks to the Vernier-principle.…”

Single-Mode Waveguides With SU-8 Polymer Core and Cladding for MOEMS Applications

“…Single-mode waveguides in SU-8 have also been fabricated before, using a variation of other polymers as cladding material [9]- [11]. The previous work done within the area clearly shows the high interest and suitability of SU-8 for integrated optical components [12]- [15]. However, materials with different intrinsic properties and structuring methods have been used as core and cladding, thereby not obtaining the aforementioned advantages of monolithic structures.…”

Lab-on-a-chip platforms based on highly sensitive nanophotonic Si biosensors for single nucleotide DNA testing

“…For achieving this goal, our first step has been the development of a novel low temperature (100 ºC) CMOS compatible microfluidic technology to create 3D embedded interconnected microfluidic channels between different substrates [20]. The microfluidic channels have a height from 40 to 60 µm and a width between 100 to 250 µm.…”