HIGHLY SENSITIVE DETECTION OF MALACHITE GREEN AND FORMALDEHYDE USING SURFACE ENHANCED RAMAN MICROFLUIDIC SENSOR

Abstract

1. A Portable Surface-enhanced Raman Scattering Sensor Integrated with a Lab-on-a-chip for Highly Sensitive Trace Analysis An integrated real-time sensing system that uses a portable Raman spectrometer and a micropillar array chip has been developed for sensitive trace analysis. The problem of poor detection sensitivity, caused by miniaturization in the portable Raman spectrometer, was overcome by using the surface-enhanced Raman scattering (SERS) technique. The problem of poor reproducibility in the SERS detection, caused by different particle sizes and inhomogeneous degrees of aggregation, was also overcome by using continuous flow and homogeneous mixing between the analytes and nanocolloidal silver in a micropillar array microfluidic chip. Two hazardous materials, dipicolinic acid and malachite green, were quantitatively analysed using our integrated portable Raman sensor system. The observed limit of detection was estimated to be 200 ppb and 500 ppb, respectively. Our proposed analytical method, using a micropillar array PDMS chip and a portable SERS system, offers a rapid and reproducible trace detection capability for hazardous materials in the field. 2. Fast and sensitive trace analysis of formaldehyde using surface enhanced Raman microfluidic sensor Formadehyde is an organic compound used as a building material or a household product. It is very harmful for human health even at low concentration levels and can cause irritation of eyes, nose, throat, and skin. Therefore, there has been an urgent need to develop a fast and sensitive detection technique for its trace analysis at a low concentration. In this research, we report a novel detection method of formaldehyde based on the SERS microfluidic sensor. First, the Schiff’s reagent was reacted with formaldehyde to form a SERS-active product. Second, this product was adsorbed onto silver nanoparticles under a flowing condition in a microdroplet chip. Finally, sensitive SERS signals of the product were measured and quantitatively analyzed. This method overcomes the drawbacks such as a time-consuming in sample preparation and a long detection time of conventional formaldehyde analysis. This novel detection technique has a strong potential for the trace analysis of other environmentally toxic samples.