Vladimir Matvejev

Integrated Waveguide Structure for Highly Sensitive THz Spectroscopy of Nano-Liter Liquids in Capillary Tubes

Terahertz dielectric spectroscopy permits the study of biomolecular interactions. However, water induces high attenuation of electromagnetic waves in the THz frequency range, obscuring the response of biomolecules. The developed sensor overcomes this problem by concentrating the THz wave propagating in an integrated waveguide on a small liquid volume contained within a capillary tube. Detailed electromagnetic modeling shows efiective interaction between the THz waves and liquids. Transmission measurement results for capillary tubes fllled with water and methanol mixtures demonstrate a substantial increase in sensitivity to changes of liquid permittivity. The current integrated sensor facilitates THz spectroscopy of biological liquids: a case study on bufiered human serum albumin solution demonstrates a great potential to complement biochemical analytical tools.

Exponent monte carlo for quick statistical circuit simulation

The main goals of this article are to report an implementation and a quantitative study of Exponent Monte Carlo, an enhanced version of Monte Carlo for verifying high circuit yield in the presence of random process variations. Results on industry-grade standard cell netlists and compact models in 45nm show that EMC predicts reasonable results at least 1,000 times faster than MC.

Wet silicon bulk micromachined THz waveguides for low-loss integrated sensor applications

Wet Si bulk micromachining enables producing hexagonally shaped waveguides (WH) with superior performance and are applicable to low THz frequency range. We discuss the fabrication process, hexagonal cross-section analysis, and balance between loss mitigation and operational frequency band of WH.

INEXPENSIVE AND EASY FABRICATION OF MULTI- MODE TAPERED DIELECTRIC CIRCULAR PROBES AT MILLIMETER WAVE FREQUENCIES

Tapered dielectric flbers are widely used in the near fleld microscopy to focus the incident beam or collect near fleld signal. Single mode is always required so that the geometrical dimension of the waveguide is smaller than the wavelength. This paper proposes an inexpensive and easy fabrication of multimode tapered Te∞on probe which has bigger dimensions than the wavelength. The fleld distribution in and outside the probe is analyzed by the total internal re∞ection theorem and solid core circular dielectric waveguide theory. Simulations are carried out in Microwave Studio CST. Novel applications based on focal points in and outside the probe are discussed, especially dielectric permittivity sensing of biomolecules using a capillary tube is emphasized by the simulations and experiments.

A label-free detector for liquid chromatography systems using mm-wave technology: First proof of concept

The development of millimeter-wave (mm-wave) technology has enabled the study of bio-molecular interactions by means of electromagnetic waves with frequencies between 30 and 300GHz. In this study, an attempt has been made to exploit the possibility of mm-wave technology as alternative detection technique for liquid chromatographic (LC) systems. The goal is to design and fabricate a label-free mm-wave detector that is compatible with LC systems. As proof-of-concept experiments, the UV absorbing compounds praziquantel and trans-stilbene-oxide as well as a non-UV absorbing compound sorbitol are injected in an open capillary as well as a capillary with stationary phase and measured by both mm-wave and UV detectors. The in-house developed mm-wave detector is capable of detecting all compounds without the need for labelling. Although the detection limit of such detector still needs to be verified and occasionally improved in the future, it already shows great potential as an additional detection technique for LC systems.

Bio-chemical Process Monitoring with Terahertz Sensor

An in-house developed Label-free Immobilization-free Terahertz (THz) sensor has shown its potential in various applications [1]. In this paper, we present the experimental results in the field of High Performance Liquid Chromatography (HPLC) and protein crystallization. Ultra-Violet (UV) detectors are very commonly used as a detection technique in HPLC systems. However, it relies on labelling when target substances do not absorb UV light. Therefore, it has the drawback of increased cost and time consumption. Our experimental result shows that THz sensor has the potential to replace UV sensor integrated on the HPLC machine as it is able to detect both UV and non-UV absorbing substances without labelling. Meanwhile, the THz sensor is also deployed for the first time to follow a protein crystallization process.

Subterahertz sensor in microfluidic devices for on-line determination and control of ethanol concentration

This paper reports on the performance of a subterahertz (THz) liquid sensor tool coupled to a microfluidic platform. Contactless and on-line measurements are demonstrated for the determination of ethanol concentration and controlling by a micromixer device. The authors have developed a label-free chemical sensing methodology coupling a subterahertz sensor technology to microfluidic devices fabricated on glass and polydimethylsiloxane. They demonstrated on-line sensing and control of ethanol concentration on demand. The THz-microfluidic sensing strategy represents a versatile tool for fast and easy integration in microfluidic devices, for concentration detection and linear control of binary mixture concentration in a contactless mode using microreactors in laminar flow and fast mixing mechanism by convection.

THz Bio-chemical Sensing Capabilities with High Performance SIW Based Sensor on nL-Volume Liquids in Capillary

Label-free and online bio-chemical detection proved to be possible with THz waves, which would open alternative ways to a myriad of applications in the chemical, biological and medical fields such as integrated micro-reactor monitors, PCR monitoring, faster and cheaper drug discovery. However some technological challenges need to be surmounted, especially low sensitivity and large sample quantity, before practical applications can be implemented. These challenges are tackled here by an integrated sensor approach, whereby a specially developed substrate integrated waveguide is used in combination with capillary tube to maximally exploit the dynamic range of the measurement system. The sensor performance is benchmarked with water/alcohol mixtures. A selection of measurements on biological substances is presented to demonstrate the bio-chemical sensing capabilities. The developed approach shows outstanding sensitivity performance for extremely small sample quantities.