An optimised nuclear magnetic resonance (NMR) detector design has been developed to allow in situ NMR observation of sub mM concentrations of sample within a 2 l sample volume on a microfluidic chip. The detector is a new design of double micro-stripline detector that is compatible with functional lab-on-a-chip devices. The design has been optimised using nite element analysis taking into account both the shape of the sample chamber and the resonator. The sensitivity of this detector compares favourably with other micro-NMR systems. The ability to observe low concentrations allows direct analysis of cell metabolomics on a chip within 20 minutes of experiment time. The detector has been adapted to resonate at 2 frequencies. This opens the possibility of heteronuclear NMR experiments without compromising the sensitivity of the probe. The sensitivity is sufficient to demonstrate the ability to study changes in the structure of proteins when binding to a substrate. Also explored in this work is another detector design the inductively coupled planar microcoil. Finite element analysis has allowed accurate simulation of these microcoils.