ABSTRACT
Per- and polyfluoroalkyl substances (PFAS) are highly toxic pollutants of significant concern as they are being detected in water, air, fish and soil. They are extremely persistent and accumulate in plant and animal tissues. Traditional methods of detection and removal of these substances use specialised instrumentation and require a trained technical resource for operation. Molecularly imprinted polymers (MIPs), polymeric materials with predetermined selectivity for a target molecule, have recently begun to be exploited in technologies for the selective removal and monitoring of PFAS in environmental waters. This review offers a comprehensive overview of recent developments in MIPs, both as adsorbents for PFAS removal and sensors that selectively detect PFAS at environmentally-relevant concentrations. PFAS-MIP adsorbents are classified according to their method of preparation (e.g., bulk or precipitation polymerization, surface imprinting), while PFAS-MIP sensing materials are described and discussed according to the transduction methods used (e.g., electrochemical, optical). This review aims to comprehensively discuss the PFAS-MIP research field. The efficacy and challenges facing the different applications of these materials in environmental water applications are discussed, as well as a perspective on challenges for this field that need to be overcome before exploitation of the technology can be fully realised.
ABSTRACT
This article reports an original concept enabling the rapid fabrication of continuous-flow microfluidic chips with a programmable and reconfigurable geometry. The concept is based on a digital microfluidic platform featuring an array of individually addressable electrodes. A selection of electrodes is switched on sequentially to create a de-ionized (DI) water finger specific pattern, while the surrounding medium consists of liquid-phase paraffin. The water displacement is induced by both electrowetting on dielectric and liquid dielectrophoresis phenomena. Once the targeted DI water pattern is obtained, the chip temperature is lowered by turning on an integrated thermoelectric cooler, forming channel structures made of solidified paraffin with edges delimitated by the DI water pattern. As a result, the chip can be used afterwards to conduct in-flow continuous microfluidic experiments. This process is resettable and reversible by heating up the chip to melt the paraffin and reconfigure the microchannel design on demand, offering the advantages of cost, adaptability, and robustness. This paper reports experimental results describing the overall concept, which is illustrated with typical and basic fluidic geometries.
