TY  - JOUR
A1  - Schusser, Sebastian
A1  - Poghossian, Arshak
A1  - Bäcker, Matthias
A1  - Krischer, M.
A1  - Leinhos, Marcel
A1  - Wagner, P.
A1  - Schöning, Michael Josef
T1  - An application of field-effect sensors for in-situ monitoring of degradation of biopolymers
JF  - Sensors and actuators B: Chemical
N2  - The characterization of the degradation kinetics of biodegradable polymers is mandatory with regard to their proper application. In the present work, polymer-modified electrolyte–insulator–semiconductor (PMEIS) field-effect sensors have been applied for in-situ monitoring of the pH-dependent degradation kinetics of the commercially available biopolymer poly(d,l-lactic acid) (PDLLA) in buffer solutions from pH 3 to pH 13. PDLLA films of 500 nm thickness were deposited on the surface of an Al–p-Si–SiO2–Ta2O5 structure from a polymer solution by means of spin-coating method. The PMEIS sensor is, in principle, capable to detect any changes in bulk, surface and interface properties of the polymer induced by degradation processes. A faster degradation has been observed for PDLLA films exposed to alkaline solutions (pH 9, pH 11 and pH 13).
Y1  - 2015
U6  - http://dx.doi.org/10.1016/j.snb.2014.10.058
SN  - 1873-3077 (E-Journal); 0925-4005 (Print)
VL  - 207, Part B
SP  - 954
EP  - 959
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Murib, M. S.
A1  - Yeap, W. S.
A1  - Martens, D.
A1  - Liu, X.
A1  - Bienstman, P.
A1  - Fahlman, M.
A1  - Schöning, Michael Josef
A1  - Michiels, L.
A1  - Haenen, K.
A1  - Serpengüzel, A.
A1  - Wagner, Patrick
T1  - Photonic studies on polymer-coated sapphire-spheres : a model system for biological ligands
JF  - Sensors and actuators A: Physical
N2  - In this study we show an optical biosensor concept, based on elastic light scattering from sapphire microspheres. Transmitted and elastic scattering intensity of the microspheres (radius 500 μm, refractive index 1.77) on an optical fiber half coupler is analyzed at 1510 nm. The 0.43 nm angular mode spacing of the resonances is comparable to the angular mode spacing value estimated using the optical size of the microsphere. The spectral linewidths of the resonances are in the order of 0.01 nm, which corresponds to quality factors of approximately 105. A polydopamine layer is used as a functionalizing agent on sapphire microspherical resonators in view of biosensor implementation. The varying layer thickness on the microsphere is determined as a function of the resonance wavelength shift. It is shown that polymer functionalization has a minor effect on the quality factor. This is a promising step toward the development of an optical biosensor.
Y1  - 2015
U6  - http://dx.doi.org/10.1016/j.sna.2014.11.024
SN  - 1873-3069 (E-Journal); 0924-4247 (Print)
VL  - 222
SP  - 212
EP  - 219
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Breuer, Lars
A1  - Raue, Markus
A1  - Kirschbaum, M.
A1  - Mang, Thomas
A1  - Schöning, Michael Josef
A1  - Thoelen, R.
A1  - Wagner, Torsten
T1  - Light-controllable polymeric material based on temperature-sensitive hydrogels with incorporated graphene oxide
JF  - Physica status solidi (a)
N2  - Poly(N-isopropylacrylamide) (PNIPAAm) hydrogel films with incorporated graphene oxide (GO) were developed and tested as light-stimulated actuators. GO dispersions were synthesized via Hummers method and characterized toward their optical properties and photothermal energy conversion. The hydrogels were prepared by means of photopolymerization. In addition, the influence of GO within the hydrogel network on the lower critical solution temperature (LCST) was investigated by differential scanning calorimetry (DSC). The optical absorbance and the response to illumination were determined as a function of GO concentration for thin hydrogel films. A proof of principle for the stimulation with light was performed.
Y1  - 2015
U6  - http://dx.doi.org/10.1002/pssa.201431944
SN  - 1862-6319
VL  - 212
IS  - 6
SP  - 1368
EP  - 1374
PB  - Wiley
CY  - Weinheim
ER  -