In this paper we discuss some physical limits for scaling of transistors and conducting paths inside of semiconductor integrated circuits (ICs). Since 40 years only a semiconductor technology, mostly the CMOS and the TTL technologies, are used for fabrication of integrated circuits on an industrial scale. Miniaturization of electronic devices in integrated circuits has technological limits and physical limits as well. In 2010 best parameters of commercial ICs shown the Intel Core i5-670 processor manufactured in the technology of 32 nm. Its clock frequency in turbo mode is 3.73 GHz. A forecast of the development of the semiconductor industry (ITRS 2011) predicts that sizes of electronic devices in ICs circuits will be smaller than 10 nm in the next 10 years. At least 5 physical effects should be taken into account if we discuss limits of scaling of integrated circuits.
The paper presents the results of a numerical study devoted to the hydraulic properties of a network of parallel triangular microchannels (hydraulic diameter Dh = 110 um). Previous experimental investigations had revealed that pressure drop through the microchannels system dramatically increases for the Reynolds number exceeding value of 10. The disagreement of the experimental findings with the estimations of flow resistance based on the assumption of fully developed flow were suspected to result from the so-called scale effect. Numerical simulations were performed by using the classical system of flow equations (continuity and Navier-Stokes equations) in order to explain the observed discrepancies. The calculations showed a very good agreement with the experimental results proving that there is no scale effect for the microchannels considered, i.e. the relevance of the constitutive flow model applied was confirmed. It was also clearly indicated that the excessive pressure losses in the high Reynolds number range are due to the secondary flows and separations appearing in several regions of the microchannel system.
A measurement system for 256-channel in vitro recordings of brain tissue electrophysiological activity is presented in the paper. The system consists of the brain tissue life support system, Microelectrode Array (MEA), conditioning Application Specific Integrated Circuits (ASIC’s) for signals conditioning, Digitizer and PC application for measurement data presentation and storage. The life support system keeps brain tissue samples in appropriately saturated artificial cerebrospinal fluid at a very stable temperature. The MEA consists of two hundred and fifty-six 40 μm diameter tip-shaped electrodes. The ASIC’s performs amplification and filtering of the 256-field and action potential signals. The Digitizer performs simultaneous data acquisition from 256 channels 14 kS/s sample rate and 12-bit resolution. The resulting byte stream is transmitted to the PC via USB (Universal Serial Bus). Preliminary tests confirm that the system is capable of keeping the extracted brain tissue active (hippocampal formation slices) and simultaneously to record action potentials, as well as local theta field potentials with very small amplitudes from multiple neurons