Martin Sommer

Intrinsic device-to-device variation in graphene field-effect transistors on a Si/SiO2 substrate as a platform for discriminative gas sensing

Arrays of nearly identical graphene devices on Si/SiO2 exhibit a substantial device-to-device variation, even in case of a high-quality chemical vapor deposition (CVD) or mechanically exfoliated graphene. We propose that such device-to-device variation could provide a platform for highly selective multisensor electronic olfactory systems. We fabricated a multielectrode array of CVD graphene devices on a Si/SiO2 substrate and demonstrated that the diversity of these devices is sufficient to reliably discriminate different short-chain alcohols: methanol, ethanol, and isopropanol. The diversity of graphene devices on Si/SiO2 could possibly be used to construct similar multisensor systems trained to recognize other analytes as well.

Employment of Electric Potential to Build a Gas-Selective Response of Metal Oxide Gas Sensor Array

This paper presents an approach to design multisensor microarrays for electronic nose instruments employing a metal oxide thin film whose spatial gas-sensitive properties are locally differentiated by electric potential. The measurement of local potential as a sensor signal over the metal oxide film serves to build a gas discriminating pattern which can be selectively identified by pattern recognition techniques. The gas sensitivity studies have revealed a higher gas response on the film areas, which are activated by positive potential, than that at earth potential. The gas-recognition capability of potential patterns is, at least, comparable with the one of conductance patterns recorded at the same microarrays differentiated by nonhomogeneous spatial heating. The experimental data are discussed in terms of oxide surface charging by adspecies coming through the ambient air. The suggested approach could be considered for designing reproducible multisensor systems on a single-chip platform.

Toward new gas-analytical multisensor chips based on titanium oxide nanotube array

Reliable environmental monitoring requires cost effective but highly sensitive and selective gas sensors. While the sensitivity of the sensors is improved by reducing the characteristic dimensions of the gas-sensing material, the selectivity is often approached by combining the sensors into multisensor arrays. The development of scalable methods to manufacture such arrays based on low-dimensional structures offers new perspectives for gas sensing applications. Here we examine an approach to produce multisensor array chips based on the TiOx nanotube layers segmented by multiple Pt strip electrodes. We study the sensitivity and selectivity of the developed chip at operating temperatures up to 400 °C towards organic vapors in the ppm range. The results indicate that the titania nanotubes are a promising material platform for novel cost-effective and powerful gas-analytical multisensor units.

UV assisted room temperature gas recognition with SnO 2 nanowires

Room temperature operated recognition of gases and smells by UV activated SnO2 nanowires are demonstrated in this paper. The recognition and separation of CO, isopropanol, and benzene in concentrations down to 10 ppm in dry and humid air is shown. Also the smells of different burnt materials or fruit can be distinguished via linear discriminant analysis. The detection of the gases is possible within 10 s.

Integrated wire grid polarizer and plasmonic polarization beam splitter

An ultra-compact, low loss, high extinction ratio polarization beam splitter is proposed for the SOI platform The device is 3.5 um in length and provides more than 11 dB extinction ratio with less than 1 dB plasmonic losses.

The Gas‐Sensing Characteristics Of Percolating 2‐D SnO2 Nanowire Mats As A Platform For Electronic Nose Devices

We describe gas‐sensing characteristics of percolating SnO2 nanowire (NW) mats employed in Electronic nose (E‐nose) instrument. The current strategy is based on combining bottom‐up technology of NWs growth and top‐down fabrication of multisensor microarray according to KAMINA (KArlsruhe Micro NAse) E‐nose architecture. Such issues of the NW‐based multisensor systems are discussed as gas‐sensing stability, gas sensitivity and gas classification using Linear Discriminant Analysis (LDA) pattern recognition technique.

SnO 2 Nanowire-Based Aerosol Jet Printed Electronic Nose as Fire Detector

A smart fire detector preferably reacting before smoke breaks out and providing information about the substance going to start burning, is an unaccomplished hope for fire safety authority since decades. Here, we present an easy method to fabricate, hence cheap, smell detecting electronic nose (e-Nose) which is capable to operate as low cost smart detector for fire-related smells as an example application. Smell sensing in principle is achieved by measuring the resistance pattern of 16 sub-sensor elements combined on a single chip and a subsequent pattern recognition technique using multivariate data analysis. The sensing material of one single sub-sensor is SnO2 nanowires, fabricated in a high temperature condensation process and dispersed on digital aerosol jet printed interdigitated Au structure. Assisted by UV illumination, the basic chip performance was characterized using laboratory gases, such as synthetic air, Isopropanol, CO and Benzene and the detection limit of the e-Nose exposed to Benzene was measured to be 2.2 ppm. It needs only 6.6 mW to activate such sensor for continuous operation. As an application of such system, a smart fire detector was demonstrated, which can not only detect the pre burning smell of several substances, but it can also identify previously taught patterns of burning smell of test substances like, cotton, beech, and PCB.

The Potentiodynamic Bottom-up Growth of the Tin Oxide Nanostructured Layer for Gas-Analytical Multisensor Array Chips

We report a deposition of the tin oxide/hydroxide nanostructured layer by the potentiodynamic method from acidic nitrate solutions directly over the substrate, equipped with multiple strip electrodes which is employed as a gas-analytical multisensor array chip. The electrochemical synthesis is set to favor the growth of the tin oxide/hydroxide phase, while the appearance of metallic Sn is suppressed by cycling. The as-synthesized tin oxide/hydroxide layer is characterized by mesoporous morphology with grains, 250–300 nm diameter, which are further crystallized into fine SnO2 poly-nanocrystals following heating to 300 °C for 24 h just on the chip. The fabricated layer exhibits chemiresistive properties under exposure to organic vapors, which allows the generation of a multisensor vector signal capable of selectively distinguishing various vapors.

High-speed Plasmonic Modulators

Plasmonic modulators integrated with silicon photonic circuits are discussed. First, a 29 μm long phase modulator operating at 40Gbit/s is demonstrated. Then, an absorption modulator is presented exploiting the plasma effect in metal oxide layers.

Chip-to-chip plasmonic interconnects and the activities of EU project NAVOLCHI

In this paper, the chip-to-chip interconnection architecture adopted by the EU-project NAVOLCHI are discussed. The plasmonic physical layer consisting of a plasmonic nanoscale laser, a modulator, an amplifier and a detector is introduced. Current statuses of the plasmonic devices are reviewed.