arXiv subjects

Heiko Schäfer-Eberwein

Publications and source records attributed to Heiko Schäfer-Eberwein.

3 recordsLinked to original sources

arXiv2020

Ultrasensitive THz Biosensor for PCR-free cDNA detection based on frequency selective surfaces

THz technologies are a powerful tool for label-free detection of biomolecules. However, significant reduction of the lower detection limit is required to apply THz-sensors in biomedical diagnosis. This paper reports an ultrasensitive THz-biosensor based on asymmetric double split ring resonators (aDSRR) for the direct label- and PCR-free detection of DNA at physiologically relevant concentrations. We introduce selective functionalization and localized electric field concentration to enhance aDSRR sensitivity and specificity. The sensor characteristics are demonstrated using the human tumor marker MIA in cDNA samples produced from total RNA without PCR-amplification. Measurements of DNA samples with concentrations as low as $1.55\,\times\,10^{-12}\,$mol/l are presented.

physics.app-ph↗

arXiv2015

Optimizing the Optical and Electrical Properties of Graphene Ink Thin Films by Laser-annealing

We demonstrate a facile fabrication technique for graphene-based transparent conductive films. Highly flat and uniform graphene films are obtained through the incorporation of an efficient laser annealing technique with one-time drop casting of high-concentration graphene ink. The resulting thin films are uniform and exhibit a transparency of more than 85% at 550 nm and a sheet resistance of about 30 kΩ/sq. These values constitute an increase of 45% in transparency, a reduction of surface roughness by a factor of four and a decrease of 70% in sheet resistance compared to unannealed films.

cond-mat.mtrl-sci↗

arXiv2014

Heterojunction Hybrid Devices from Vapor Phase Grown MoS$_{2}$

We investigate a vertically-stacked hybrid photodiode consisting of a thin n-type molybdenum disulfide (MoS$_{2}$) layer transferred onto p-type silicon. The fabrication is scalable as the MoS$_{2}$ is grown by a controlled and tunable vapor phase sulfurization process. The obtained large-scale p-n heterojunction diodes exhibit notable photoconductivity which can be tuned by modifying the thickness of the MoS$_{2}$ layer. The diodes have a broad spectral response due to direct and indirect band transitions of the nanoscale MoS$_{2}$. Further, we observe a blue-shift of the spectral response into the visible range. The results are a significant step towards scalable fabrication of vertical devices from two-dimensional materials and constitute a new paradigm for materials engineering.

cond-mat.mtrl-sci↗