Fiber-Top Cantilevers: A New Sensor on the Tip of a Fiber

icromachined cantilevers are the most elementary example of minia-turized sensors. A free-standing rectangu-lar beam can often detect changes in the chemical, biological and physical proper-ties of the surroundings with sensitivity comparable to much more complicated devices. It is therefore not surprising that this simple design is still at the heart of several scientific instruments. ese instruments rely on the pos-sibility of measuring the vertical position of the suspended edge of the beam with atomic accuracy—a level of precision that can be achieved by electronic readout or optical techniques. Electronic read-outs are not always compatible with the environment where measurements must ture, surface topography, etc.). We have already demonstrated that one can rely on this technology for the development of opto-mechanical transducers,1,2 thermal1 and chemical3 sensors, as well as atomic force microscopes.4 e monolithic structure of the device, which completely eliminates any problem associated with the alignment of the opti-cal components, and the absence of elec-tronic contacts on the sensing head make our fiber-top design the ideal solution to all those situations in which sensors must operate in confined space and/or in the presence of harsh conditions. Furthermore, the simplicity of the working principle well adapts to possible implementations of user-friendly devices for utilization outside research laboratories (e.g., hospitals, quality inspection areas, homeland security checkpoints, space missions, combat fields, etc.), where instruments must often be used by personnel who do not possess the technical skills required to operate complex readouts. It is thus reasonable to envision that, in a near future, other fiber-top sensors will be developed for both scientific experiments and technological applications.