The article presents miniature detection system capable of selective detection of vapor traces of different explosives. The article presents: the principles of operation, compares optical and electronic detection systems, explains the function of chemical modification. It presents the implementation of MEMS differential sensor, and procedure for chemical functionalization. Electronics and noise optimization is a key procedure to achieve excellent sensitivity. The article describes also the calibration procedure, system level simulations and its results, implementation of a complete measurement system, implementation of vapor generator used for laboratory measurements and some initial laboratory and field measurements. The resulting sensor system has excellent sensitivity that is in the range of 3ppT for TNT and 0.5ppt for RDX
COBISS.SI-ID: 25306919
In this paper the authors discuss the issues related to the self-awareness of high-resolution, mixed-signal circuits and systems, based on Σ−Δ ADC, which is the most important and sensitive module and the key element for an analogue to digital conversion. The basic methodology and framework for improving the “self-awareness” of such systems are presented in the article. The methodology is based on efficient real-time measurements of a high-resolution, mixed-signal system using pseudo random signal source, real-time calculation of a distance between responses, the possibility to adapt measured circuit to minimize the distance, and changing the parameters of a reference system according to learned rules. The calculation of the distance between the system and its reference are theoretically analyzed and verified using Matlab model. The response of a system together with the response of high precision analogue to digital converter (ADC) is compared to the response of a bit-true model of a reference digital circuit. The differences are calculated using simple area-efficient cross-correlation algorithm. The algorithm together with adaptation strategy and tuning circuitry form the basis for “self-awareness” of mixed-signal circuits.
COBISS.SI-ID: 9641044
Operations of a self-mixing terahertz signal detector combined with a low noise amplifier and a properly balanced - folded dipole or slot antenna for concentrating millimeter wave signals to NMOS detectors is described. The detector was optimized to 300 GHz signals. Achieved noise equivalent power (NEP) was estimated to 320 pW/√Hz while the total output referred noise of 2.1 μV//√Hz was measured at amplifier gain of 46 dB.
COBISS.SI-ID: 9127252
A room-temperature planar microbolometer double-dipole antenna for the focal-plane-array imaging at 300 GHz is presented. The fabricated antenna with a Titan bolometer consists of the full-wavelength parallel-dipole array on a thin nitride membrane, double impedance-transformation sections and low-pass-filter readout taps on a silicon substrate. The simulated antenna directivity at 300 GHz is about 11.7 dBi and agrees well with the measured radiation pattern. The radiation efficiency is about 85 % and the estimated bandwidth more than 200 GHz. A responsivity of 40 V/W and a noise-equivalent power of 4 x 10-11 W/√Hz have been measured, respectively.
COBISS.SI-ID: 9246292
In this article we present part of the design methodology, modeling and efficient simulation of high performance micro-electromechanical ∑Δ modulator. The method is based on converting continuous-time model of the MEMS sensor and eventual analog loop filter into discrete time equivalent using impulse invariant transformation. The methodology is valid for any “MEMS based cantilever” sensor operating in a closed loop, where mechanical transfer function does not provide adequate noise shaping to reach high accuracy and resolution. Using proposed methodology makes possible to efficiently design, predict the behavior and stability of the loop and efficient system level simulations.
COBISS.SI-ID: 9246548