Optical fiber-based force transducer for microscale samples

Abstract

We discuss the design, instrumentation, and calibration of a versatile force transducer with feedback control, called the Micro-Extensional Rheometer (MER). A force range of eight decades (1–108 pN) and a displacement range of four decades (10–105 nm) with a spatial resolution of the order of nanometers are accessible with the instrument. A feedback-loop algorithm is used to control the commanded force or the extensional strain on the sample and implement different rheometric protocols such as step-strain, step-force, exponential strain, among others. The device may also be used to measure the forces exerted by active suspensions, pulling neurons, etc