Nanoparticle Printing for Microfluidic Applications: Bipolar Electrochemistry and Localized Raman Sensing Spots

Abstract

The local integration of metal nanoparticle films on 3D-structured polydimethylsiloxane (PDMS)-based microfluidic devices is of high importance for applications including electronics, electrochemistry, electrocatalysis, and localized Raman sensing. Conventional processes to locally deposit and pattern metal nanoparticles require multiple steps and shadow masks, or access to cleanroom facilities, and therefore, are relatively imprecise, or time and cost-ineffective. As an alternative, we present an aerosol-based direct-write method, in which patterns of nanoparticles generated via spark ablation are locally printed with sub-mm size and precision inside of microfluidic structures without the use of lithography or other masking methods. As proof of principle, films of Pt or Ag nanoparticles were printed in the chambers of a multiplexed microfluidic device and successfully used for two different applications: Screening electrochemical activity in a high-throughput fashion, and localized sensing of chemicals via surface-enhanced Raman spectroscopy (SERS). The versatility of the approach will enable the generation of functional microfluidic devices for applications that include sensing, high-throughput screening platforms, and microreactors using catalytically driven chemical conversions.

Accessibility study of porous materials at the single-particle level as evaluated within a microfluidic chip with fluorescence microscopy

“…The experiments were performed using microfluidic devices consisting of two PDMS layers and a glass slide (Figure S1), as previously reported. 36,37 The top layer contains four chambers, which allow the performance of three experiments in parallel under the same conditions while keeping a reference chamber to control for photobleaching (Figure 1C). In the experiments, each chamber is loaded with various porous SiO 2 particles.…”

Accessibility Study of Porous Materials at the Single Particle Level as Evaluated within a Microfluidic Chip with Fluorescence Microscopy

“…Finally, we investigated through simulations how internal diffusion, adsorption, and external mass transfer affected the shape of the uptake curves. The experiments were performed using microfluidic devices consisting of two PDMS layers, and a glass slide (Figure S1), as previously reported 36,37 . The top layer contains four chambers, which allow the performance of three experiments in parallel under the same conditions while keeping a reference chamber to control for photobleaching (Figure 1C).…”