MPa, E l is calculated as ~7.0 nm which is rather small and leads to miniscule deformation not measurable by optical microscopy. It has been shown recently that geometric amplification can enhance this deformation such that it becomes measurable . For example, thin wall of a microchannel embedded inside a layer of PDMS deforms reversibly when a liquid is inserted into it and the extent of deformation remains high enough that it can be measured using an optical profilometry. We have used this phenomenon here to monitor the progress of a surface reaction occurring at the inside wall of the microchannel.