Sensitive and selective determination of metal ions (Li, Na, K, Cd, Pd, etc.) is challenging due to the interference from interfering metals. Yet, it is crucial for many applications such as environmental monitoring, biomedical diagnostics, and battery manufacturing.
To develop novel, cost-effective, specific, and easy-to-use sensors, we leveraged the power of microfluidics and advanced functional materials including synthetic receptors like ion-imprinted polymers, thereby developing the next generation of electrochemical sensors.
Below is a summary of few related projects.
1. Sensitive and Specific Detection of Metal Ions in Water Using a Microfluidic Sensor with an Standalone Ion-Imprinted Polymer Membrane
We developed an innovative electrochemical sensor designed for precise and specific quantification of metal ions in water bodies. The sensor integrates an in-situ prepared, thickness-controlled, UV-curable standalone membrane made of syntetic receptors such as Ion-Selective Polymers (ISPs) or Ion-Imprinted Polymers (IIPs) within a Polymethacrylate (PMMA)-based microfluidic chip. The ISP membrane, a synthetic receptor containing specific functional groups, selectively interacts with target ions based on their chemistry. This interaction alters the electrochemical signal, which is measured using two cost-effective electrodes in-situ prepared on either side of the ISP membrane, thereby amplifying both sensitivity and specificity.
To develop novel, cost-effective, specific, and easy-to-use sensors, we leveraged the power of microfluidics and advanced functional materials including synthetic receptors like ion-imprinted polymers, thereby developing the next generation of electrochemical sensors.
Below is a summary of few related projects.
1. Sensitive and Specific Detection of Metal Ions in Water Using a Microfluidic Sensor with an Standalone Ion-Imprinted Polymer Membrane
We developed an innovative electrochemical sensor designed for precise and specific quantification of metal ions in water bodies. The sensor integrates an in-situ prepared, thickness-controlled, UV-curable standalone membrane made of syntetic receptors such as Ion-Selective Polymers (ISPs) or Ion-Imprinted Polymers (IIPs) within a Polymethacrylate (PMMA)-based microfluidic chip. The ISP membrane, a synthetic receptor containing specific functional groups, selectively interacts with target ions based on their chemistry. This interaction alters the electrochemical signal, which is measured using two cost-effective electrodes in-situ prepared on either side of the ISP membrane, thereby amplifying both sensitivity and specificity.
Our membrane-integrated microfluidic sensors significantly improved limits of detection and quantification as well as specificity compared to other similar techniques like ion selective electrodes (ISEs). For instance, it provided an LOD of 0.14 ppm, an LOQ of 0.25 ppm, and a sensitivity of 0.0024 µA/ppm for Na ion detection, surpassing the performance of prior studies.
2. Enhanced Sensitivity in Microfluidic Electrochemical Sensing Platforms Utilizing Dean Flow Recirculation in Curved Microchannels
Over the past decade, there has been a significant improvement in the limit of detection, selectivity, and sensitivity of microfluidic electrochemical sensors (MES), primarily attributed to advancements in electrode materials and the adoption of signal amplification techniques. Innovative electrode materials improve sensitivity and selectivity in MES by enhancing electron transfer kinetics and surface area. Signal amplification techniques, such as enzyme-based and nanoparticle-based methods, further boost sensitivity by amplifying the electrochemical signal upon analyte detection. However, both techniques pose extra costs and complexity to the system and may not be available for all target analytes.
We hypothesized that laminar flow in MES might limit analyte-electrode interactions, potentially reducing sensor effectiveness. To address this, we examined the impact of secondary (Dean) flow, passively induced by curvilinear microchannels, on MES output using square wave voltammetry (SWV). Results showed significant enhancement in curved channels over straight ones due to increased interactions from Dean flow recirculation.
This is a pioneering work and the first of its kind in harnessing microfluidic Dean flow for enhanced electrochemical detection.
Over the past decade, there has been a significant improvement in the limit of detection, selectivity, and sensitivity of microfluidic electrochemical sensors (MES), primarily attributed to advancements in electrode materials and the adoption of signal amplification techniques. Innovative electrode materials improve sensitivity and selectivity in MES by enhancing electron transfer kinetics and surface area. Signal amplification techniques, such as enzyme-based and nanoparticle-based methods, further boost sensitivity by amplifying the electrochemical signal upon analyte detection. However, both techniques pose extra costs and complexity to the system and may not be available for all target analytes.
We hypothesized that laminar flow in MES might limit analyte-electrode interactions, potentially reducing sensor effectiveness. To address this, we examined the impact of secondary (Dean) flow, passively induced by curvilinear microchannels, on MES output using square wave voltammetry (SWV). Results showed significant enhancement in curved channels over straight ones due to increased interactions from Dean flow recirculation.
This is a pioneering work and the first of its kind in harnessing microfluidic Dean flow for enhanced electrochemical detection.
