Bilsay Sümer

Rolling and Spinning Friction Characterization of Fine Particles Using Lateral Force Microscopy Based Contact Pushing

In this paper, we have utilized Lateral Force Microscopy (LFM) based mechanical pushing of micro/nano-objects to study adhesion and friction characterization at the micro/nanoscale. Continuum micro/nano-friction models for particle rolling, spinning and sliding cases are discussed for general particle–substrate interfaces. A rolling resistance model using the Double–Hertz model is devoloped for such general interfaces. Using the friction models, the effect of work of adhesion, effective Youngs modulus, and contact radius at the particle–substrate interface are studied in detail. Combining friction models with experimental particle pushing vertical and lateral force data, the critical frictional interface parameters such as critical rolling distance and the interfacial shear strength are measured for a polystyrene particle and glass substrate interface. Results show that the critical rolling distance varies with the particle radius, and it is measured to be 42, 84 and 128 nm on average for 5, 10 and 15 μm radii particles, respectively. Next, using the particle spinning experimental data, the interfacial shear strength of the particle–substrate interface is measured as 9–15 MPa.

An experimental analysis of elliptical adhesive contact

The elliptical adhesive contact is studied experimentally utilizing two hemicylinders of elastomeric poly(dimethylsiloxane) (PDMS). Experimental results are compared with the recent approximate Johnson–Kendall–Roberts (JKR) theory for elliptical contacts, and the deviation of the experiments from this theory is discussed in detail. To do this, the cylinders are placed with different skew angles with respect to each other in order to emulate the effect of orientation. The maximum adhesion force and the size of the contact zone are determined experimentally under the action of surface energy. The difference of the maximum adhesion force between experiments and theory is found to increase as the contact area goes from mildly elliptical to slim elliptical contact. Similarly, it is observed that the contact area can be approximated to have elliptical geometry for a wide range of skew angles while a deviation is observed for slim elliptical contacts. Moreover, the reduction in the contact area is observed to be...

Cross-talk compensation in atomic force microscopy

In this work, calibration and correction of cross-talk in atomic force microscopy (AFM) is demonstrated. Several reasons and effects of this inherent problem on experimental results are discussed. We propose a general procedure that can be used on most AFM systems to compensate for cross-talk on the cantilever bending and twisting signals. The method utilizes two initial experiments on a flat surface to achieve an affine transformation between the measured signals and the actual signals. Using this transformation directly on the voltage signals allows us to remove the detrimental effects of cross-talk on AFM-based force measurement experiments. The achieved transformation matrix can be turned into a simple circuit and applied online, by users who have access to the raw signals in the AFM head. As a case study, a lateral deflection based mechanical characterization test for a poly(methyl methacrylate) microfiber that is suspended on a trench is investigated in terms of the effectiveness of the cross-talk compensation.

Tip based robotic precision micro/nanomanipulation systems

This paper surveys the history of tip based micro/nanomanipulation systems and the contributions of the authors in this topic. Atomic force microscope or scanning tunnerling microscope type of microscopes has been used as nanorobotic manipulation systems since 1990. Using single or multiple tips, many mechanical, electrical, and chemical micro/nanomanipulation applications have demonstrated. The authors contributed to teleoperated and automated control of such systems and also developed new tip based micro/nanomanipulation methods to draw polymer micro/nanofibers and create nanowires on substrates precisely and repeatedly.

Investigation of adhesion and friction of an isotropic composite pillar

In this work, studies are carried out on the adhesion and friction of composite pillars contact with a smooth flat surface. The composite pillar is obtained by allocating additive metal particles to a polymer matrix. The aluminum micron-sized particles are added to a polymer matrix in different mass ratios, which is aimed at an alteration of structural properties such as the stiffness and damping that is likely to permit adhesion and friction properties to be tuned accordingly. The results demonstrate that incorporating aluminum particles to a polymer matrix yields a loss of adhesion, and metal particles have a minor influence on the change of friction force for different sliding velocities.

Assessment of Friction Force between a PDMS Pillar and a Flat Glass Substrate

The friction force between a polydimethylsiloxane (PDMS) pillar in contact with a flat glass substrate is examined. The friction between the pillar and the glass is achieved with lateral loading of the glass under constant velocity. The friction force during the lateral motion is estimated by modelling the motion of the pillar as a lumped parameter system. The parameters of the lumped system are presented as equivalent mass, stiffness and damping components with addition of the contact interaction. Validation of the model is accumulated with experiments and the relative error between the analytical and experimental results is around %10.

Analytical and Experimental Analysis on Kinetics of a Laparoscopic Surgery Tool

Each laparoscopic surgery tool has specific design and task, which includes grasping, cutting, clamping, retraction etc. for surgery. This study deals with kinetic analysis of a conventional laparoscopic grasper in order to obtain a simple and valid analytical model that allows optimization of tool dimension, and verification of the model with experimental results. Additionally, simplified analytical model is compared with previously developed analytical model. The simplified model has the same results in calculation of actuator and grasper force compared to its predecessor. With the simplified analytical model, maximum error between the analytical and the experimental results is up to 2.8% in specific parameters.