TY  - JOUR
A1  - Zhong-Fu, X.
A1  - Shan-Shan, M.
A1  - Jia-Qian, Z.
A1  - Xun-Lin, Q.
A1  - Ye-Wen, Z.
A1  - Gerhard, Reimund
A1  - Künstler, Wolfgang
T1  - Piezoelectric activity and its stability of polytetrafluoroethylene (PTFE) films
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Yilmaz, Sükrü
A1  - Wirges, Werner
A1  - Bauer-Gogonea, Simona
A1  - Bauer, Siegfried
A1  - Gerhard, Reimund
A1  - Michelotti, F.
A1  - Toussaere, E.
A1  - Levenson, R.
A1  - Liang, J.
A1  - Zyss, Joseph
T1  - Dielectric, pyroelectric and electro-optic monitoring of the cross-linking process and photo-induced poling of Red Acid Magly
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Xia, Zhongfu
A1  - Gerhard, Reimund
A1  - Künstler, Wolfgang
A1  - Wedel, Armin
A1  - Danz, Rudi
T1  - High surface-charge stability of porous polytetrafluoroethylene electret films at room and elvated temperatures
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Wirges, Werner
A1  - Wegener, Michael
A1  - Voronina, Olena
A1  - Zirkel, Larissa
A1  - Gerhard, Reimund
T1  - Optimized preparation of elastically soft, highly piezoelectric, cellular ferroelectrets from nonvoided poly(ethylene terephthalate) films
N2  - Electrically charged cellular polymer films can exhibit very high piezoelectric activity and are therefore more and more often employed in advanced electromechanical and electro-acoustical transducers. In this paper, we report an optimized sequence of steps for preparing such ferroelectrets from commercial nonvoided ploy(ethylene terephthalate) (PETP) films by means of foaming with CO2 biaxial mechanical stretching, controlled void inflation, and bipolar electric charging. The nonvoid PETP films foamed with supercritical CO2 at a suitably high pressure and subsequently annealed for stabilization. The cellular foam structure was further optimized by means of well controlled biaxial stretching in a commercial stretcher and sometimes subsequent inflamation in a pressure chamber. Bipolar electric charging of the internal voids was achieved through the application of high electric fields in an SF0 atmosphere. The new optimized PETP ferroelectric exhibit quite large piezoelectric coefficients up to almost 500 pCN(-1), for which unusually low elastic stiffness of only around 0.3 MPa are essential. The PETP foam ferroelectrics posses unclamped thickenss-extension resonance frequences between approximately 120 and 250 kHz, and are thus highly suitable for several established as well as novel ultrasonic-transductant applications.
Y1  - 2007
UR  - http://onlinelibrary.wiley.com/doi/10.1002/adfm.200600162/pdf
U6  - https://doi.org/10.1002/adfm.200600162
ER  - 
TY  - JOUR
A1  - Wirges, Werner
A1  - Przyrembel, G.
A1  - Brinker, Walter
A1  - Gerhard, Reimund
A1  - Klemberg-Sapieha, J.
A1  - Martinu, L.
A1  - Poitras, D.
A1  - Wertheimer, M. R.
T1  - Metallised viscoelastic control layers for light-valve projection displays
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Wertheimer, Michael R.
A1  - St-Georges-Robillard, Amelie
A1  - Lerouge, Sophie
A1  - Mwale, Fackson
A1  - Elkin, Bentsian
A1  - Oehr, Christian
A1  - Wirges, Werner
A1  - Gerhard, Reimund
T1  - Amine-rich organic thin films for cell culture - possible electrostatic effects in cell-surface interactions
JF  - Japanese journal of applied physics
N2  - In recent communications from these laboratories, we observed that amine-rich thin organic layers are very efficient surfaces for the adhesion of mammalian cells. We prepare such deposits by plasma polymerization at low pressure, atmospheric pressure, or by vacuum-ultraviolet photo-polymerization. More recently, we have also investigated a commercially available material, Parylene diX AM. In this article we first briefly introduce literature relating to electrostatic interactions between cells, proteins, and charged surfaces. We then present certain selected cell-response results that pertain to applications in orthopedic and cardiovascular medicine: we discuss the influence of surface properties on the observed behaviors of two particular cell lines, human U937 monocytes, and Chinese hamster ovary cells. Particular emphasis is placed on possible electrostatic attractive forces due to positively charged R-NH3+ groups and negatively charged proteins and cells, respectively. Experiments carried out with electrets, polymers with high positive or negative surface potentials are added for comparison.
Y1  - 2012
U6  - https://doi.org/10.1143/JJAP.51.11PJ04
SN  - 0021-4922
VL  - 51
IS  - 11
PB  - Japan Soc. of Applied Physics
CY  - Tokyo
ER  - 
TY  - JOUR
A1  - Weinhold, Till
A1  - Wegener, Michael
A1  - Künstler, Wolfgang
A1  - Seiß, Martin
A1  - Görne, Thomas
A1  - Gerhard, Reimund
T1  - Porous polytetrafluoroethylene (PTFE) single-film space-charge electrets with high piezoelectric coefficients
Y1  - 2000
SN  - 0537-9989
ER  - 
TY  - JOUR
A1  - Wegener, Michael
A1  - Wirges, Werner
A1  - Richter, Kristin
A1  - Künstler, Wolfgang
A1  - Gerhard, Reimund
T1  - Charge stability and piezoelectric properties of porous fluoro-polymer space-charge electrets in layer systems
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Wegener, Michael
A1  - Wirges, Werner
A1  - Paajanen, Mika
A1  - Gerhard, Reimund
T1  - Charging behaviour and thermal stability of porous and non-porous polytetrafluoroethylene (PTFE) electrets
Y1  - 2007
SN  - 978-1-4244-1482-6
ER  - 
TY  - JOUR
A1  - Wegener, Michael
A1  - Wirges, Werner
A1  - Gerhard, Reimund
A1  - Dansachmüller, M.
A1  - Schwödiauer, R.
A1  - Bauer-Gogonea, Simona
A1  - Bauer, Siegfried
A1  - Paajanen, Mika
A1  - Minkkinen, Hannu
A1  - Raukola, J.
T1  - Controlled inflation of voids in cellular polymer ferroelectrets : optimizing electromechanical transducer properties
N2  - When exposed to sufficiently high electric fields, polymer-foam electret materials with closed cells exhibit ferroelectric-like behavior and may therefore be called ferroelectrets. In cellular ferroelectrets, the influence of the cell size and shape distributions on the application-relevant properties is not yet understood. Therefore, controlled inflation experiments were carried out on cellular polypropylene films, and the resulting elastical and electromechanical parameters were determined. The elastic modulus in the thickness direction shows a minimum with a corresponding maximum in the electromechanical transducer coefficient. The resonance frequency shifts as a function of the elastic modulus and the relative density of the inflated cellular films. Therefore, the transducer properties of cellular ferroelectrets can be optimized by means of controlled inflation. (C) 2004 American Institute of Physics
Y1  - 2004
ER  -