Influências do tipo de sonda, substrato e meio circundante nas curvas de força de adesões por AFM

Abstract

In this work we use force curves obtained through the atomic force microscope (AFM) to study the influence of probes, substrates and media on tip-substrate adhesions. The probes HYDRA – 100NG, ACCESS – EFM and ACT – SS were used, whose tips are made of silicon (Si) and silicon coated with Platinum (Pt). The experiments were carried out in three stages. In the first step, we carried out experiments by interacting the probes on a glass substrate in air, and, through the force curves obtained, it was observed that there was a greater adhesion in the interaction of the HYDRA - 100NG and ACT -SS probes with Si tips. In the second step, for each probe used, measurements of the interaction with two different substrates were performed: glass and mica, in air. For this case, the AFM force curves showed that the adhesion of the HYDRA – 100NG and ACT –SS probes on the mica decreased while the adhesion on the mica of the probe with Pt coated tip, ACCESS – EFM, increased. In the third stage of the experiment, for each probe and for each substrate, measurements were carried out in air and in liquid, and in all the curves obtained, a decrease in the adhesive force was observed in relation to the measurements made in air. These results are important, since many studies using AFM need to know how the behavior of adhesion forces in tip-substrate interactions, such as the functionalization of tips and substrates for the construction of nanobiosensors based on AFM.