Chemical and biological sensors based on micro/nanocantilevers

 

A dependence of the mechanical response of AFM microcantilevers on temperature, air humidity and composition of atmosphere was observed, pointing out to the possibility of the use of microcantilevers as highly sensitive components of sensors for the measurement of numerous physical and chemical parameters and opened a new, very dynamical and prospective research field – microcantilever sensors.

     The main advantages of microcantilever sensors are their high sensitivity, fast response, low cost, low energy consumption and portability (ensuring in-situ measurements). A large number of microcantilever sensors has been developed for measurement of temperature, force, mass, flow, infrared radiation, magnetic fields, air humidity, gas concentration, ion concentration in solutions, detection of the presence of certain biomolecules (proteins, DNA) or viruses in solutions, harmful substances, etc. So diverse applications required the development of microcantilevers with varied designs and composition (different shapes, homogeneous or bimaterial, etc.), fabricated in different materials, adjusted for operation in vacuum, gas or liquid environment, as well as the development of different modes of operation, excitation and detection of the mechanical response of cantilevers. The improvement of performance of certain types of sensors with a decrease of the cantilever dimensions brought to the development of nanocantilevers.

     In the field of sensors, theoretical research comprises the analysis of mechanical behaviour of micro/nanocantilevers with homogeneous composition, as well as bimaterial structures, exposed to different stimuli (particle adsorption from gas or liquid phase, temperature change, electromagnetic field). The analysed structures are intended for realization of chemical sensors, biosensors, sensors for measurement of electromagnetic forces and infrared radiation sensors. By developing theoretical models of fluctuation phenomena in micro/nanocantilevers, the researchers of CMT achieve important results at world level. These models ensure the calculation of certain types as well as the total value of noise and the minimum detectable signal. They ensure insight into the dependence of these important sensor parameters on geometry (shape and dimensions) of cantilevers and operating conditions, which ensures optimization of design and operating conditions of sensors with microcantilevers in the sense of noise minimization and improvement of minimum detectable signal. CMT researchers fabricated unique microcantilevers with piezoresistive and optical displacement detection. Gold microcantilevers for detection of small EM forces are also designed and fabricated in CMT. Gold microcantilevers are also intended for gaseous mercury detection, and characterisation of these sensors is planned for the future period.