On-demand concentration of an analyte on laser-printed polytetrafluoroethylene

Abstract

Textured surfaces with non-uniform wettability allow the achievement of extremely high values of analyte concentration in an evaporating droplet for ultrasensitive detection systems.

Ultrasensitive SERS-Based Plasmonic Sensor with Analyte Enrichment System Produced by Direct Laser Writing

“…1a,b). Such a pillar arrangement with a central site coated with superhydrophilic SiO 2 was recently shown to work as an efficient analyte-enrichment system [24]. This system supported the Cassie-Baxter state of the water droplet that evaporated on its surface, permitting to deposit 98% of analyte dissolved in the droplet onto the central site [24].…”

“…Laser processing was performed using 180-fs second-harmonic (515 nm) laser pulses generated by a regenerative amplified ytterbium-doped potassium gadolinium tungstate (Yb:KGW) fs-laser system (Pharos, Light Conversion Ltd.). First, fs-laser radiation was used to fabricate a device for analyte enrichment, which was recorded on a smooth mechanically polished PTFE surface following the procedure and design previously developed and optimized in [24]. Laser pulses generated at repetition rate 10 KHz were focused on a PTFE surface using a dry microscope objective with numerical aperture (NA) of 0.15, while the sample was arranged on a PC-driven nanopositioning platform (Aerotech Gmbh.)…”

“…The droplet contour was used then to calculate the drop volume V and CA using standard techniques [27]. More detailed information regarding evaluation of device's wetting characteristics can be found elsewhere [24]. Correlated reflection and dark-field (DF) back-scattering spectra were used to characterize plasmonic performance of the Au-coated spallative textures.…”

“…These agglomerated colloids were further used as SERS-active site for analyte identification [15,17]. However, as the SERS performance achieved in the experiments reaches a single-molecule detection level, this approach requires rigorous and intricate purification of the colloids after their synthesis to provide background-free reliable detection of the analyte.Direct laser processing of various materials with nano-and femtosecond (fs) laser pulses is known to be a facile and inexpensive technology for fabrication of both plasmon-active nanostructures [18] and topographies permitting to control surface wetting [19][20][21][22][23][24][25][26]. However, no attempts were made so far to utilize direct laser processing to create a fully-functional device that would combine efficient analyte enrichment with ultrasensitive SERS-based detection.Here, we report an easy-to-implement device for SERS-based identification of various analytes dissolved in water droplets at trace concentrations.…”

“…Direct laser processing of various materials with nano-and femtosecond (fs) laser pulses is known to be a facile and inexpensive technology for fabrication of both plasmon-active nanostructures [18] and topographies permitting to control surface wetting [19][20][21][22][23][24][25][26]. However, no attempts were made so far to utilize direct laser processing to create a fully-functional device that would combine efficient analyte enrichment with ultrasensitive SERS-based detection.…”