MEMS cantilever-based chemical sensor provides an excellent platform for early disease detection in plants using the indirect detection method based on volatile organic compounds (VOCs) profile. Static sensing mode is used for the detection of target VOC. We focus on citrus canker disease in citrus leaves (specifically Ponkan mandarin leaves) caused by Xanthomonas citri subsp. citri (Xcc), which induced Linalool that acts as an indicator to incite a resistance response counter to Xcc. Polyethylene Glycol (PEG) coated on electrostatically actuated MEMS cantilever beam acts as the immobilisation layer. We utilise electrical detection as a simple readout mechanism for nanometre deflection sensing. When designing sensors, it is important to take into account the quantitative analysis of the surface force caused by adsorption. Thus, a detailed study based on quantum chemical calculations for hydrogen bond formation in PEG and Linalool is needed. The analysis is performed by Density Functional Theory (DFT). The study enables the calculation of adsorption induced surface stress, which is utilised for the design, optimisation and analysis of MEMS cantilever-based chemical sensor.