The Human Immunodeficiency Virus is a dangerous virus that, when left untreated, causes the Acquired Immunodeficiency Syndrome-an infection that has a debilitating effect on the immune system; therefore, making the affected individual extremely susceptible to secondary infections such as tuberculosis, encephalopathy and numerous cancers. Almost 36 million people have died of complications due to HIV/AIDS since inception, and early detection of HIV helps in the prevention of AIDS. Commercial P24 antigen assays can measure only between 5-25 pg/ml, and this can lead to false negative to P24 antigen, which is the major protein in the HIV composition. This necessitates the detection of lower levels of P24 antigen; and we propose a microcantilever sensor model using COMSOL Multiphysics. The effect of varying design parameters such as shape, dimensions and materials on the sensitivity of the microcantilever is studied and an optimal design for the microcantilever is suggested.