Wojciech Dera, M.Sc., Eng.

Department of Theory of Continuous Media and Nanostructures (ZTOCiN)
Division of Polymer Physics (PFP)
position: specialist
telephone: (+48) 22 826 12 81 ext.: 107
room: 237
e-mail: wdera

Recent publications
1.Dziekoński C., Dera W., Jarząbek D.M., Method for lateral force calibration in atomic force microscope using MEMS microforce sensor, ULTRAMICROSCOPY, ISSN: 0304-3991, DOI: 10.1016/j.ultramic.2017.06.012, Vol.182, pp.1-9, 2017
Dziekoński C., Dera W., Jarząbek D.M., Method for lateral force calibration in atomic force microscope using MEMS microforce sensor, ULTRAMICROSCOPY, ISSN: 0304-3991, DOI: 10.1016/j.ultramic.2017.06.012, Vol.182, pp.1-9, 2017

Abstract:
In this paper we present a simple and direct method for the lateral force calibration constant determination. Our procedure does not require any knowledge about material or geometrical parameters of an investigated cantilever. We apply a commercially available microforce sensor with advanced electronics for direct measurement of the friction force applied by the cantilever's tip to a flat surface of the microforce sensor measuring beam. Due to the third law of dynamics, the friction force of the equal value tilts the AFM cantilever. Therefore, torsional (lateral force) signal is compared with the signal from the microforce sensor and the lateral force calibration constant is determined. The method is easy to perform and could be widely used for the lateral force calibration constant determination in many types of atomic force microscopes.

Keywords:
A precise and direct method for lateral force calibration, Inaccuracy equal to approximately 2%, Wedge method is proven to give inaccurate results

2.Jarząbek D.M., Gwiazda M., Dera W., The Influence of Alkali Metal Chloride Treatments on the Wear Resistance of Silicon Surfaces for Possible Use in MEMS, TRIBOLOGY TRANSACTIONS, ISSN: 1040-2004, DOI: 10.1080/10402004.2017.1296211, pp.1-7, 2017
Jarząbek D.M., Gwiazda M., Dera W., The Influence of Alkali Metal Chloride Treatments on the Wear Resistance of Silicon Surfaces for Possible Use in MEMS, TRIBOLOGY TRANSACTIONS, ISSN: 1040-2004, DOI: 10.1080/10402004.2017.1296211, pp.1-7, 2017

Abstract:
The wear of contacting silicon surfaces in microelectromechanical systems (MEMS) has been a longstanding concern. To address this issue, the effects of immersing silicon surfaces into alkali metal chloride solutions (LiCl, NaCl, CsCl) on their sliding friction and wear were investigated. A custom-built reciprocating tribometer was used with a sapphire ball as the counterbody. Results indicated that the friction coefficient between the silicon surface (p-doped, orientation (100)) and a sapphire ball can be reduced by up to 30% by treating the silicon surfaces in aqueous salt solutions (concentration 1 mol/L, exposure for 24 h). These modified surfaces also have higher wear resistance and a significant change in wettability. After immersion, the contact angle between the silicon surface and water was reduced by approximately 50%. These results may lead to new, simple, and inexpensive methods to increase the wear resistance of silicon surfaces for use in MEMs devices.

Keywords:
silicon surface, wear, friction, alkali metal chlorides


List of chapters in recent monographs
1.
509
Jarząbek D.M., Dera W., Ceramic Matrix Materials - Materials, Manufacturing and Engineering, Series: Advanced Composites, rozdział: The measurement of mechanical properties of interfaces in ceramic composites, Walter de Gruyter GmbH, Berlin/Boston, Printed in Germany, 5, pp.77-108, 2016

Conference abstracts
1.Jarząbek D.M., Dera W., Rymuza Z., The measurement of viscosity of ultrathin polymer films, EUROMAT 2015, European Congress and Exhibition on Advanced Materials and Processes, 2015-09-20/09-24, Warszawa (PL), pp.1, 2015
Jarząbek D.M., Dera W., Rymuza Z., The measurement of viscosity of ultrathin polymer films, EUROMAT 2015, European Congress and Exhibition on Advanced Materials and Processes, 2015-09-20/09-24, Warszawa (PL), pp.1, 2015

Abstract:
Viscosity is a very important property of thin polymer films used in modern microelectronic technology i.e. in nanoimprint lithography. Hence, in this work we present a method for viscosity of ultrathin polymer films determination. The viscosity is evaluated from the response of the oscillating piezoelectric cantilever at the end of which an indentation probe is mounted (Fig. 1a). When a polymer film is indented, the resonant frequency of the oscillations is changed and the parameters of used model (i.e. Maxwell model) can be identified. The frequency of the oscillations is equal to tens of kilohertz therefore the influence of extremely high deformation velocities can be investigated by means of this method. It is also possible to conduct the experiments in elevated temperature (up to 150 o C). The oscillations direction can be parallel as well as perpendicular to the fil m’s surface. The investigated films were made of PMMA. Their thickness ranges from a few nanometers up to 1 micrometer. The results were compared with other methods of the viscosity determination: the investigation of the creep response during nanoindentation, sinus mode nanoindentation and atomic force microscope based technique

2.Jarząbek D.M., Dera W., Rymuza Z., The measurement of viscosity of ultrathin polymer films, Nanomechanical Testing in Materials Research and Development V, 2015-10-04/10-09, Albufeira (PT), pp.1, 2015

Patents
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419571
2016-11-23
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Jarząbek D., Dera W., Dziekoński C.
Urządzenie do pomiaru lepkości cienkich warstw materiałów lepkosprężystych
PL, Instytut Podstawowych Problemów Techniki PAN
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