Adsorption induced surface-stress sensing signal originating from both vertical interface effects and intermolecular lateral interactions.

This research investigates the origin of specific molecule-adsorption induced surface-stress for micro/nano-cantilever bio/chemical sensors. Systematic discussion is presented on the contribution from types of molecule interactions to the generated surface-stress sensing signal. With the main arguments verified by our micro-cantilever sensing experiments, the origin of the adsorption induced surface-stress is, for the first time, clearly categorized into interface vertical effects and lateral interactions, which helps to comprehensively understand the surface-stress generation and overall to optimize the sensing performance of micro-cantilever chemo-mechanical sensors. The key findings of this research are that, vertically at the molecule adsorption surface, interfacial energy change and charge redistribution are the main origins of the generated surface-stress. More importantly, intermolecular lateral interactions may make a more significant contribution to the nano-mechanical surface-stress response. Compared with other lateral interactions like van der Waals force and the electrostatic coulombic effect, intermolecular hydrogen-bond intensity and steric factor easily cause much greater disparity in surface-stress.