Injection-Molded Microfluidic Device for SERS Sensing Using Embedded Au-Capped Polymer Nanocones

Abstract

To enable affordable detection and diagnostic, there is a need for low-cost and mass producible miniaturized sensing platforms. We present a fully polymeric microfluidic lab-on-a-chip device with integrated gold (Au)-capped nanocones for sensing applications based on surface-enhanced Raman spectroscopy (SERS). All base components of the device were fabricated via injection molding (IM) and can be easily integrated using ultrasonic welding. The SERS sensor array, embedded in the bottom of a fluidic channel, was created by evaporating Au onto IM nanocone structures, resulting in densely packed Au-capped SERS active nanostructures. Using a Raman active model analyte, trans-1,2-bis-(4pyridyl)-ethylene, we found a surface-averaged SERS enhancement factor of ∼5 × 10 6 with a relative standard deviation of 14% over the sensor area (2 × 2 mm 2 ), and a 18% signal variation among substrates. This reproducible fabrication method is costeffective, less time consuming, and allows mass production of fully integrated polymeric, microfluidic systems with embedded high-density and high-aspect ratio SERS sensor.

Sandwich‐based surface‐enhanced Raman scattering probes for detection and quantification of malaria

“…SERS is an ultrasensitive vibrational fingerprinting tool that can detect analytes at low concentrations [25]. With the gold standard POCTs lateral flows showing questionable sensitivity at low concentrations, SERS offers enhanced sensitivity and quantification capabilities.…”

Wafer‐Scale Polymer‐Based Transparent Nanocorals with Excellent Nanoplasmonic Photothermal Stability for High‐Power and Superfast SERS Imaging

“…Gold is chosen due to its stability which extends shelf life of the WTNC SERS substrates. During gold deposition, a shadow mask with a specific pattern can be employed on the wafer to render bare SU‐8 areas, facilitating further processes to be performed, such as laser dicing and microfluidic integration by ultrasonic wielding . A photograph of a WTNC SERS substrate taken from its backside is shown in Figure f.…”

“…To further demonstrate the thermal stability of the WTNC substrate, its performance is compared with a transparent TOPAS‐based ( T g of TOPAS = 134 °C) SERS substrate with similar surface‐averaged SERS EF of ≈1 × 10 6 . Before introducing BPE analytes onto the substrates, a laser scan is performed on the WTNC and the TOPAS‐based substrate in the dotted areas shown in Figure S2a,b in the Supporting Information with I SC = 50 and 15 kW cm −2 , respectively.…”

“…Recently, polymer‐based SERS substrates have attracted immense attention due to their distinctive advantages, e.g., i) cheap production using large‐scale and high‐throughput fabrication processes, such as injection molding and screen printing, ii) easy integration with microfluidics platforms allowing elaborated, on‐chip sample pretreatments which are important for sensing applications, and iii) optical transparency, which enables SERS signals to be probed from the backside of the substrate. This property is extremely useful for direct detection of trace chemicals on target surfaces, e.g., ractopamine (feed additive) residue on pork, malachite green (highly toxic) on fish, and Raman imaging of molecules using SERS‐active metafilms .…”

Recent progress of microfluidics in surface‐enhanced Raman spectroscopic analysis

“…Meanwhile, microfabrication techniques selected to SERS-active substrate preparation are relative to the supporting material of microchips (as shown in Table 1). Materials, including Si [24,25], glass [26], polymethyl methacrylate (PMMA) [27], PDMS [28,29], cyclic olefin copolymer (COC) [30], polycarbonate (PC) [31], polystyrene (PS) [32], and paper [33][34][35], have been employed for fabricating SERS detection microchips.…”