TY  - JOUR
A1  - Laux, Eva-Maria
A1  - Ermilova, Elena
A1  - Pannwitz, Daniel
A1  - Gibbons, Jessica
A1  - Hölzel, Ralph
A1  - Bier, Frank Fabian
T1  - Dielectric Spectroscopy of Biomolecules up to 110 GHz
JF  - Frequenz
N2  - Radio-frequency fields in the GHz range are increasingly applied in biotechnology and medicine. In order to fully exploit both their potential and their risks detailed information about the dielectric properties of biological material is needed. For this purpose a measuring system is presented that allows the acquisition of complex dielectric spectra over 4 frequency decade up to 110 GHz. Routines for calibration and for data evaluation according to physicochemical interaction models have been developed. The frequency dependent permittivity and dielectric loss of some proteins and nucleic acids, the main classes of biomolecules, and of their sub-units have been determined. Dielectric spectra are presented for the amino acid alanine, the proteins lysozyme and haemoglobin, the nucleotides AMP and ATP, and for the plasmid pET-21, which has been produced by bacterial culture. Characterisation of a variety of biomolecules is envisaged, as is the application to studies on protein structure and function.
KW  - dielectric
KW  - spectroscopy
KW  - permittivity
KW  - protein
KW  - DNA
KW  - amino acid
KW  - plasmid
Y1  - 2018
U6  - https://doi.org/10.1515/freq-2018-0010
SN  - 0016-1136
SN  - 2191-6349
VL  - 72
IS  - 3-4
SP  - 135
EP  - 140
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Qiu, Xunlin
A1  - Benjamin, Aravindan Joseph
A1  - Raman Venkatesan, Thulasinath
A1  - Schmidt, Georg C.
A1  - Soler, Ricardo Alonso Quintana
A1  - Panicker, Pramul Muraleedhara
A1  - Gerhard, Reimund
A1  - Hübler, Arved Carl
T1  - Dielectric and electroacoustic assessment of screen-printed piezoelectric polymer layers as flexible transducers
BT  - influence of the electrode material
JF  - IEEE transactions on dielectrics and electrical insulation
N2  - Here, piezoelectric transducers consisting of a P(VDF-TrFE) layer with either silver or PEDOT:PSS screen-printed electrodes are studied. The influence of electrodes on the dielectric and electroacoustic properties are studied in dielectric-spectroscopy and ferroelectric-hysteresis measurements. Only when both the bottom and the top electrodes are made of silver, the typical dielectric relaxation of the P(VDF-TrFE) layer is clearly observed. When one or two of the electrodes are of PEDOT:PSS, a Debye-like relaxation is present. Compared with silver electrodes, PEDOT:PSS electrodes allow for moderate self-healing. Consequently, samples with bottom and top PEDOT:PSS electrodes can be poled to saturation, while samples with silver electrodes can hardly be poled to saturation due to destructive electric breakdown. Acoustic transducer measurements show that silver electrodes facilitate higher and broader frequency operation, while PEDOT:PSS electrodes bring slightly lower total harmonic distortion. Overall, the acoustic performance shows no significant deviations between differently electroded samples so that silver electrodes do not offer any advantages for the transducers studied here due to their much higher tendency for destructive electric breakdown.
KW  - poly(vinylidenefluoride-trifluoroethylene) P(VDF-TrFE)
KW  - dielectric
KW  - spectroscopy
KW  - ferroelectricity and piezoelectricity in polymers
KW  - screen
KW  - printing
KW  - printed electroacoustic thin-film transducers
Y1  - 2020
U6  - https://doi.org/10.1109/TDEI.2020.008864
SN  - 1070-9878
SN  - 1558-4135
SN  - 0018-9367
VL  - 27
IS  - 5
SP  - 1683
EP  - 1690
PB  - Institute of Electrical and Electronics Engineers
CY  - New York, NY
ER  -