Summary Szabolcs Daladi

MEMS and AFM-based surface modification techniques and applications are presented in the dissertation. The starting point of the work was the investigation of tribology at microscale. Motivation of the work and general approach of the subject are presented in the introduction, followed by the background of microtribology. The most important historical progresses of tribology as science are pointed, on which the microtribology has been developed.

The requirements and the design of a microtribotester are presented in chapter three. These are based on adhesion and friction considerations for microstructures. Different in- and out-of-plane actuators, from which the microtribotester is built up, are designed and their performance is simulated by finite element method.

Chapter four comprises the work carried out on technological developments for fabrication of complex MEMS devices like the microtribosensor. It is composed of a part describing investigations on the change of residual stress of undoped sacrificial silicon-oxide at high temperature processing, a part consisting of studies carried out on optimization of reactive ion etching processes for thick silicon-oxide layers and Si_xN_y/polycrystalline-Si/silicon-oxide stacks. In the third part a novel release technique is described, which enables releasing complex MEMS structures consisting of multiple structural layers built up on multiple sacrificial layers, but which do not contain enclosed cavities.

Chapter five is based on characterization of electrothermal actuators and describes an empirical method of discriminating reversible and irreversible actuation regimes of electrothermal actuators, since their main disadvantage is the plastic deformation at high temperatures, which modifies their geometry and hence their initial neutral position.

In chapter six the fabrication process of the microtribotester is presented, and its successful operation is shown. The reason of continuing the work in the direction of atomic force microscope-based surface modification and characterization is also discussed.

Chapter seven is a prologue to the second major part of the dissertation. Basic notions related to atomic force microscopy are introduced in order to help in the interpretation of data presented in the following chapters.

A new in-situ AFM-based surface modification and characterization technique is described in chapter eight. The technique developed enlarges the possibilities of micro- and nano-tribological investigations using atomic force microscopy, since it enables in-situ wear, friction and adhesion studies for various material-couples and loading conditions.

In chapter nine further development of the AFM-probes is presented. In order to allow AFM-based fluid enabled surface modification, new probes were designed and fabricated, comprising reservoir(s) and fluidic channels in their structure. The proof of principle, based on experimental evidences, is also shown in this chapter.

Chapter ten focuses exclusively on new applications, which can only be carried out by using the AFM-probes with fluidic capabilities. In-situ AFM-based surface modification and characterization technique can be used in combination with the new probes, hence tribological investigations can be carried out with local lubrication. The utility of the micromachined fountain pen has been proven for lithographical application, such as writing with self-assembled monolayers on gold surface and by removing materials locally, in a controlled way. The micromachined fountain pen improves techniques like dip-pen lithography due to continuous fluid flow, and surface modification carried out by using pulled glass pipettes up to now. Another application, the electrochemical deposition of metal features, demonstrates the possibility to create 3-D micro/nanostructures with bottom-up approach using standard AFM equipment. All these preliminary tests provide the evidence that the new AFM-probes considerably enlarge the field of AFM-based applications. Furthermore, other opportunities have been identified such as multicomponent chemistry and cell manipulation by using dedicated AFM-probes, which can be developed based on the micromachined fountain pen.

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Home News Events Strategic Orientations research groups Publications PhD students Education MESA+ NanoLab Starting entrepreneurs Tech Park Industrial Partners Vacancies Links Sitemap Search	Summary Szabolcs Daladi MEMS and AFM-based surface modification techniques and applications are presented in the dissertation. The starting point of the work was the investigation of tribology at microscale. Motivation of the work and general approach of the subject are presented in the introduction, followed by the background of microtribology. The most important historical progresses of tribology as science are pointed, on which the microtribology has been developed. The requirements and the design of a microtribotester are presented in chapter three. These are based on adhesion and friction considerations for microstructures. Different in- and out-of-plane actuators, from which the microtribotester is built up, are designed and their performance is simulated by finite element method. Chapter four comprises the work carried out on technological developments for fabrication of complex MEMS devices like the microtribosensor. It is composed of a part describing investigations on the change of residual stress of undoped sacrificial silicon-oxide at high temperature processing, a part consisting of studies carried out on optimization of reactive ion etching processes for thick silicon-oxide layers and Si_xN_y/polycrystalline-Si/silicon-oxide stacks. In the third part a novel release technique is described, which enables releasing complex MEMS structures consisting of multiple structural layers built up on multiple sacrificial layers, but which do not contain enclosed cavities. Chapter five is based on characterization of electrothermal actuators and describes an empirical method of discriminating reversible and irreversible actuation regimes of electrothermal actuators, since their main disadvantage is the plastic deformation at high temperatures, which modifies their geometry and hence their initial neutral position. In chapter six the fabrication process of the microtribotester is presented, and its successful operation is shown. The reason of continuing the work in the direction of atomic force microscope-based surface modification and characterization is also discussed. Chapter seven is a prologue to the second major part of the dissertation. Basic notions related to atomic force microscopy are introduced in order to help in the interpretation of data presented in the following chapters. A new in-situ AFM-based surface modification and characterization technique is described in chapter eight. The technique developed enlarges the possibilities of micro- and nano-tribological investigations using atomic force microscopy, since it enables in-situ wear, friction and adhesion studies for various material-couples and loading conditions. In chapter nine further development of the AFM-probes is presented. In order to allow AFM-based fluid enabled surface modification, new probes were designed and fabricated, comprising reservoir(s) and fluidic channels in their structure. The proof of principle, based on experimental evidences, is also shown in this chapter. Chapter ten focuses exclusively on new applications, which can only be carried out by using the AFM-probes with fluidic capabilities. In-situ AFM-based surface modification and characterization technique can be used in combination with the new probes, hence tribological investigations can be carried out with local lubrication. The utility of the micromachined fountain pen has been proven for lithographical application, such as writing with self-assembled monolayers on gold surface and by removing materials locally, in a controlled way. The micromachined fountain pen improves techniques like dip-pen lithography due to continuous fluid flow, and surface modification carried out by using pulled glass pipettes up to now. Another application, the electrochemical deposition of metal features, demonstrates the possibility to create 3-D micro/nanostructures with bottom-up approach using standard AFM equipment. All these preliminary tests provide the evidence that the new AFM-probes considerably enlarge the field of AFM-based applications. Furthermore, other opportunities have been identified such as multicomponent chemistry and cell manipulation by using dedicated AFM-probes, which can be developed based on the micromachined fountain pen.