SpectIR-fluidics: completely customizable microfluidic cartridges for high sensitivity on-chip infrared spectroscopy with point-of-application studies on bacterial biofilms

Abstract

We present a generalizable fabrication method for a new class of analytical devices that merges virtually any microfluidic design with high-sensitivity on-chip attenuated total reflection (ATR) sampling using any standard...

A spectIR-fluidic reactor for monitoring fast chemical reaction kinetics with on-chip attenuated total reflection Fourier transform infrared spectroscopy

“…The spectroscopy-enhanced microfluidic reactor device (herein referred to as a “spectIR-fluidic reactor”) was prepared by plasma bonding the microchannel layers and the ATR sensing layer, as recently shown. 30 The microchannel layer was fabricated using polydimethylsiloxane (PDMS) (Sylgard184, Dow, Canada) mixed with a cross-linking agent at a 10 : 1 ratio, which was cast against a mould. The reaction device mould was fabricated by photolithography using a laminate photoresist with 50 μm thickness (SF4000, Mungolux, Germany) adhered to glass (75 × 50 mm, Fisherbrand™ Plain Glass Microslides, Fisher Scientific, USA).…”

“…For further information, the reader is referred to a previous publication that describes the fabrication process in more detail. 30…”

“…26 While transmission mode FTIR spectroscopy is, therefore, untenable for most applications, attenuated total reflection (ATR) elements have been demonstrated as an avenue to combining microfluidics and FTIR. 27–32 The technique is based on the interaction between the analyte fluid and the IR electromagnetic field which is trapped at the ATR crystal surface in the form of an evanescent wave. As such, direct IR-coupled reactions can be achieved without contacting device fabrication material, as demonstrated elsewhere.…”

“…Recently, we have demonstrated a versatile microfabrication approach called spectIR-fluidics, for the integration of a multi-ridge silicon ATR wafer (Si-ATR) into polydimethylsiloxane microfluidic devices with virtually no limit on channel geometry. 30 Coupling this with an aperture-based scanning system for low-cost chemical mapping 31 opens the door to multi-point measurements for kinetic studies. With this capability, microfluidics and FTIR spectroscopy for in situ measurements can be an accessible route to study chemical reactions with a wide range of reaction time-scales and complexities.…”

On-Chip Photonic Detection Techniques for Non-Invasive In Situ Characterizations at the Microfluidic Scale

“…The key features of this device include support for world-to-chip connections, compatibility with closed microfluidic channels of arbitrary complexity, and minimal dead volume space, providing flexibility in device design. That makes “SpectIR-fluidics” a powerful tool for lab-on-a-chip biological and chemical applications [ 105 ]. Srivastava et al, proposed a custom-designed single-bounce ATR-integrated microfluidic reactor to obtain in situ time-resolved information on chemical reactions using synchrotron IR radiation.…”