arXiv subjects

S. R. P. Silva

Publications and source records attributed to S. R. P. Silva.

2 recordsLinked to original sources

arXiv2018

Temperature Dependent Separation of Metallic and Semiconducting Carbon

Post-synthesis separation between metallic (m-SWNTs) and semiconducting (s-SWNTs) singlewall carbon nanotubes (SWNTs) is remaining a challenging process for the reliable fabrication of high performance electronic devices. Gel agarose chromatography is emerging as an efficient and large scale separation technique. However, the full (100%) separation of m-SWNTs and s-SWNTs has not been reached yet, mainly due to the lack of understanding of the separation mechanism. Here we study the temperature effect on the separation via gel agarose chromatography by varying the separation process temperatures between 6C and 50C, for four different SWNT sources. Exploiting the gel agarose micro-beads filtration technique we achieved up to 70% m-SWNTs and more than 90% s-SWNTs, independent of the source material. The process is temperature dependent, with improved yields up to 95% for s-SWNT (HiPco) at 6C. Temperature affects the sodium dodecyl sulfate SDS surfactant-micelle distribution along the SWNT sidewalls, thus helping to act as an aid in the sorting of SWNTs by electronic type. The sorted SWNTs are then used to fabricate transistors with very low OFF-currents (10^-13 A), high ON/OFF current ratio (>10^6) and improved charge carriers mobility.

cond-mat.mtrl-sci↗

arXiv2007

First human trials of a dry electrophysiology sensor using a carbon nanotube array interface

Fatigue, sleepiness and disturbed sleep are important factors in health and safety in modern society and there is considerable interest in developing technologies for routine monitoring of associated physiological indicators. Electrophysiology, the measurement of the electrical activity of biological origin, is a key technique for the measurement of physiological parameters in several applications, but it has been traditionally difficult to develop sensors for measurements outside the laboratory or clinic with the required quality and robustness. In this paper we report the results from first human experiments using a new electrophysiology sensor called ENOBIO, using carbon nanotube arrays for penetration of the outer layers of the skin and improved electrical contact. These tests, which have included traditional protocols for the analysis of the electrical activity of the brain--spontaneous EEG and ERP--indicate performance on a par with state of the art research-oriented wet electrodes, suggesting that the envisioned mechanism--skin penetration--is responsible. No ill side-effects have been observed six months after the tests, and the subject did not report any pain or special sensations on application of the electrode.

physics.med-ph↗