Stripline-based microfluidic devices for high-resolution NMR spectroscopy

A novel route towards microchip integrated NMR analysis was studied. For NMR analysis of mass-limited samples, research has focussed for decennia on microsolenoidal or planar helical detection coils on microfluidic substrates. Since these approaches suffer from static field distortion resulting in bad resolution, we have proposed a novel design which departs from circular shaped coils. The basic element in our design is an rf-stripline which can be defined in a single layer lithographic process and which is fully scalable to specific sample dimensions. Due to the non-complicated ‘coil’ geometry, the static field distortion is very low, resulting in a high resolution detection system. A microfluidic channel was integrated, which made this chip feasible for in-flow measurements. With this device we have shown an increased sensitivity compared to conventional NMR systems, and the highest NMR resolution ever achieved on chip.