Microelectrode Array With Transparent ALD TiN Electrodes.

Low noise platinum black or sputtered titanium nitride (TiN) microelectrodes are typically used for recording electrical activity of neuronal or cardiac cell cultures. Opaque electrodes and tracks, however, hinder the visibility of the cells when imaged with inverted microscope, which is the standard method of imaging cells plated on microelectrode array (MEA). Even though transparent indium tin oxide (ITO) electrodes exist, they cannot compete in impedance and noise performance with above-mentioned opaque counterparts.

Aluminum oxide mask fabrication by focused ion beam implantation combined with wet etching.

A novel aluminum oxide (Al2O3) hard mask fabrication process with nanoscale resolution is introduced. The Al2O3 mask can be used for various purposes, but in this work it was utilized for silicon patterning using cryogenic deep reactive ion etching (DRIE). The patterning of Al2O3 is a two-step process utilizing focused ion beam (FIB) irradiation combined with wet chemical etching.

Atomic layer deposition of aluminum oxide films for carbon nanotube network transistor passivation.

Ultra-thin (2-5 nm thick) aluminum oxide layers were grown on non-functionalized individual single walled carbon nanotubes (SWCNT) and their bundles by atomic layer deposition (ALD) technique in order to investigate the mechanism of the coating process. Transmission electron microscopy (TEM) was used to examine the uniformity and conformality of the coatings grown at different temperatures (80 degrees C or 220 degrees C) and with different precursors for oxidation (water and ozone). We found that bundles of SWCNTs were coated continuously, but at the same time, bare individual nanotubes remained uncoated.

Letter: A simple ion source set-up for desorption/ionization on silicon with ion mobility spectrometry and ion mobility spectrometry-mass spectrometry.

Using a simple ion source set-up, laser desorption/ionization on silicon (DIOS) was demonstrated with the use of a custom-made drift tube ion mobility spectrometer (IMS), mounted on a commercial triple quadrupole mass spectrometer, and with an IMS equipped with a Faraday plate detector. DIOS was tested by mobility measurement of tetrapropylammonium iodide, tetrabutylammonium iodide and tetrapentylammonium iodide, whilst 2,6-di-tert- butylpyridine was used as a standard. The reduced mobilities measured for the test halides are in concordance with previously obtained ion mobility spectrometry-mass spectrometry data.

Imaging conduction pathways in carbon nanotube network transistors by voltage-contrast scanning electron microscopy.

The performance of field-effect transistors based on single-walled carbon nanotube (SWCNT) networks depends on the electrical percolation of semiconducting and metallic nanotube pathways within the network. We present voltage-contrast scanning electron microscopy (VC-SEM) as a new tool for imaging percolation in a SWCNT network with nano-scale resolution. Under external bias, the secondary-electron contrast of SWCNTs depends on their conductivity, and therefore it is possible to image the preferred conduction pathways within a network by following the contrast evolution under bias in a scanning electron microscope.

Lithography-free fabrication of carbon nanotube network transistors.

A novel non-lithographic technique for the fabrication of carbon nanotube thin film transistors is presented. The whole transistor fabrication process requires only one mask which is used both to pattern transistor channels based on aerosol synthesized carbon nanotubes and to deposit electrodes by metal evaporation at different angles. An important effect of electrodynamic focusing was utilized for the directed assembly of transistor channels with feature sizes smaller than the mask openings.

Carbon nanotube thin film transistors based on aerosol methods.

We demonstrate a fabrication method for high-performance field-effect transistors (FETs) based on dry-processed random single-walled carbon nanotube networks (CNTNs) deposited at room temperature. This method is an advantageous alternative to solution-processed and direct CVD grown CNTN FETs, which allows using various substrate materials, including heat-intolerant plastic substrates, and enables an efficient, density-controlled, scalable deposition of as-produced single-walled CNTNs on the substrate directly from the aerosol (floating catalyst) synthesis reactor. Two types of thin film transistor (TFT) structures were fabricated to evaluate the FET performance of dry-processed CNTNs: bottom-gate transistors on Si/SiO2 substrates and top-gate transistors on polymer substrates.

Analysis of amphetamines and fentanyls by atmospheric pressure desorption/ionization on silicon mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry and its application to forensic analysis of drug seizures.

The suitability of atmospheric pressure desorption/ionization on silicon mass spectrometry (AP-DIOS-MS) and matrix-assisted laser desorption ionization mass spectrometry (AP-MALDI-MS) for the identification of amphetamines and fentanyls in forensic samples was studied. With both ionization techniques, the mass spectra recorded showed abundant protonated molecules, and the background did not disturb the analysis. The use of tandem mass spectrometry (MS/MS) allowed unambiguous identification of the amphetamines and fentanyls.