In recent years several surface stress sensors based on microcantilevers have been developed for biosensing [1–4]. Since these sensors are made using standard microfabrication processes, they can be easily made in an array format, making them suitable for high-throughput multiplexed analysis. Specific reactions occurring on one surface (enabled by selective modification of the surface a priori) of the sensor element change the surface stress, which in turn causes the sensor to deflect. The magnitude and the rate of deflection are then used to study the reaction. The microcantilevers in these sensors are usually fabricated using material like silicon and its oxides or nitrides. The high elasticity modulus of these materials places limitations on the sensitivity and sensor geometry. Alternately polymers, which have a much lower elastic modulus when compared to silicon or its derivatives, offers greater design flexibility, i.e. allow the exploration of innovative sensor configurations that can have higher sensitivity and at the same time are suitable for integration with microfluidics and electrical detection systems.
Surface stress sensors for detection of chemical and biological species
