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Magnetoelectric (magnetic/piezoelectric) heterostructures bring new functionalities to develop novel transducer devices such as (wireless) sensors or energy harvesters and thus have been attracting research interest in the last years. We have studied the magnetoelectric coupling between Metglas films (2826 MB) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) in a laminate structure. The metallic Metglas film itself served as bottom electrode and as top electrode we used an electrically conductive polymer, poly(3,4-ethylene-dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). Besides a direct electrical wiring via a graphite ink, a novel contactless readout method is presented using a capacitive coupling between the PEDOT:PSS layer and an electrode not in contact with the PEDOT:PSS layer. From the experimental result we determined a magnetoelectric coupling of 1445 V/(cm·Oe) at the magnetoelastic resonance of the structure, which is among the highest reported values for laminate structures of a magnetostrictive and a piezoelectric polymer layer. With the noncontact readout method, a magnetoelectric coupling of about 950 V/(cm·Oe) could be achieved, which surpasses previously reported values for the case of direct sample contacting. 2D laser Doppler vibrometer measurements in combination with FE simulations were applied to reveal the complex vibration pattern resulting in the strong resonant response. [ABSTRACT FROM AUTHOR]

Water-solubleconducting polymers are of interest to enable moreversatile processing in aqueous media as well as to facilitate interactionswith biomolecules. Here, we report a substituted poly(3,4-ethylenedioxythiophene)derivative (PEDOT-S:H) that is fully water-soluble and self-doped.When electrochemically oxidizing a PEDOT-S:H thin film, the film detachesfrom the underlying electrode. The oxidation of PEDOT-S:H starts withan initial phase of swelling followed by cracking before it finallydisrupts into small flakes and detaches from the electrode. We investigatedthe detachment mechanism and found that parameters such as the size,charge, and concentration of ions in the electrolyte, the temperature,and also the pH influence the characteristics of detachment. Whenoxidizing PEDOT-S:H, the positively charged polymer backbone is balancedby anions from the electrolyte solution and also by the sulfonategroups on the side chains (more self-doping). From our experiments,we conclude that detachment of the PEDOT-S:H film upon oxidation occursin part due to swelling caused by an inflow of solvated anions andassociated water and in part due to chain rearrangements within thefilm, caused by more self-doping. We believe that PEDOT-S:H detachmentcan be of interest in a number of different applications, includingaddressed and active control of the release of materials such as biomoleculesand cell cultures. [ABSTRACT FROM AUTHOR]

Adherent cells cultured in vitro must usually, at some point, be detached from the culture substrate. Presently, the most common method of achieving detachment is through enzymatic treatment which breaks the adhesion points of the cells to the surface. This comes with the drawback of deteriorating the function and viability of the cells. Other methods that have previously been proposed include detachment of the cell substrate itself, which risks contaminating the cell sample, and changing the surface energy of the substrate through thermal changes, which yields low spatial resolution and risks damaging the cells if they are sensitive to temperature changes. Here cell culture substrates, based on thin films of the ferroelectric polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) co-polymer, are developed for electroactive control of cell adhesion and enzyme-free detachment of cells. Fibroblasts cultured on the substrates are detached through changing the direction of polarization of the ferroelectric substrate. The method does not affect subsequent adhesion and viability of reseeded cells. [ABSTRACT FROM AUTHOR]