We investigate the properties of the Polymers nanofibers for its application as sensors element. Hence, are very important the geometrical, mechanical and electrical properties of the fibers in order to determine the working range, the sensibility and the minimal detection limits of the fiber. We produce the fibers by the electrospinning methods; it is a simple and quick technique for producing fibers with nanoscale diameters from a wide range of materials. In this process, a strong electric field causes a viscous solution to form a Taylor cone, from which a thin fluid jet is formed. This fluid jet may harden by a variety of processes and become a continuous fiber, which is collected at the negative electrode as electrospun, see figure.
Here we present the first step in order to determine the geometrical and the mechanical properties of the Polyethylene oxide fibers. We have deposited PEO electrospun fibers by electrospinning over a glass plate and used the AFM nanoindentation method to calculate the Young’s modulus of the fiber, and its geometrical properties also by Atomic Force Microscope. In order to calculate the Young’ modulus we used nanoindentation based on contact mechanic model. We present the results of the calculation of the Young's modulus of the fiber and the dependence between the Young’s modulus and its diameter. From the results we have observed an exponential dependence between the Young’s modulus and the diameter.
To apply the nanoindentation model we need to know the geometry of the cantilever’s tip of the AFM. This information is not always possible to obtain from the data sheet of the AFM-cantilever and when this information is not available, we calculate the geometry of the cantilever’s tip using Confocal Laser Scanning Microscope (CLSM). With this method we can calculate the face angle of the tip, which we needed for the Hertz model. Here we present these results, the angle and the 3D shape of the tip, calculated by CLSM, see figure.