Pulse mode operation of Love wave devices for biosensing applications

In this work we present a novel pulse mode Love wave biosensor that monitors both changes in amplitude and phase. A series of concentrations of 3350 molecular weight poly(ethylene glycol) (PEG) solutions are used as a calibration sequence for the pulse mode system using a network analyzer and high frequency oscilloscope. The operation of the pulse mode system is then compared to the continuous wave network analyzer by showing a sequence of deposition and removal of a model mass layer of palmitoyl-oleoyl-sn-glycerophosphocholine (POPC) vesicles. This experimental apparatus has the potential for making many hundreds of measurements a minute and so allowing the dynamics of fast interactions to be observed

Fast waveform metrology : generation, measurement and application of sub-picosecond electrical pulses

This thesis describes work performed at the National Physical Laboratory to improve the electrical risetime calibration of instruments such as fast sampling oscilloscopes. The majority of the work can be divided into four sections: development of an ultrafast optoelectronic pulse generator; measurement of fast electrical pulses with an electrooptic sampling system; de-embedding of transmission line and transition effects as measured at different calibration reference planes; and calibration of an oscilloscope. The pulse generator is a photoconductive switch based on low-temperature Gallium Arsenide, which has a very fast carrier recombination time. Sub-picosecond electrical pulses are produced by illuminated a planar switch with 200 fs optical pulses from a Ti: sapphire laser system. The pulses are measured using a sampling system with an external electro-optic probe in close proximity to the switch. The electro-optic sampling system, with a temporal resolution better than 500 fs, is used to measure the electrical pulses shape at various positions along the planar transmission line. The results are compared to a pulse propagation model for the line. The effects of different switch geometries are examined. Although the pulse generator produces sub-picosecond pulses near to the point of generation, the pulse is shown to broaden to 7 ps after passing along a length of transmission line and a coplanar-coaxial transition. For a sampling oscilloscope with a coaxial input connector, this effect is significant. Frequency-domain measurements with a network analyser, further electro-optic sampling measurements, and the transmission line model are combined to find the network transfer function of the transition. Using the pulse generator, the electro-optic sampling system and the transition knowledge, a 50 GHz sampling oscilloscope is calibrated. The determination of the instrument step response(nominal risetime 7 ps) is improved from an earlier value of 8.5 -3.5 / +2.9 ps to a new value of 7.4 -2.1 / +1.7 ps with the calibration techniques described

Waveform characterization of calibration-pulse generators for EMI measuring receivers

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents the waveform characterization of calibration pulse generators intended to evaluate the response to pulses of the weighting detectors in CISPR 16-1-1 measuring receivers. First, the standard requirements of the reference pulses are described, and the pulse generators calibration methods based on waveform measurements are briefly discussed. Then, high-resolution time domain measurements are used for characterizing the waveforms of a commercial calibration-pulse generator in terms of rise/fall time, pulse width, mean voltage of the upper state, repetition frequency, and area. Moreover, the results above are used for estimating the spectral density of the impulses, their corresponding quasi-peak level, the pulses bandwidth, and the breakpoint frequencies. Finally, the measurement uncertainty is estimated for CISPR bands A, B, and C/D. Results are in good agreement with other calibrations performed during an intercomparison exercise and the uncertainty satisfy the target ±0.5 dB and 1% given in standards for the impulse area and pulse repetition frequency respectively.Postprint (author's final draft

Waveform Approach for Assessing Conformity of CISPR 16-1-1 Measuring Receivers

An alternative approach for assessing the conformity of electromagnetic interference measuring receivers with respect to the baseline CISPR 16-1-1 requirements is proposed. The method’s core is based on the generation of digitally synthesized complex waveforms comprising multisine excitation signals and modulated pulses. The superposition of multiple narrowband reference signals populating the standard frequency bands allows for a single-stage evaluation of the receiver’s voltage accuracy and frequency selectivity. Moreover, characterizing the response of the weighting detectors using modulated pulses is more repeatable and less restrictive than the conventional approach. This methodology significantly reduces the amount of time required to complete the verification of the receiver’s baseline magnitudes, because time-domain measurements enable a broadband assessment while the typical calibration methodology follows the time-consuming narrow band frequency sweep scheme. Since the reference signals are generated using arbitrary waveform generators, they can be easily reproduced from a standard numerical vector. For different test receivers, the results of such assessment are presented in the 9 kHz–1 GHz frequency range. Finally, a discussion on the measurement uncertainty of this methodology for assessing measuring receivers is given.Postprint (author's final draft

System measures response time of photomultiplier tubes

Calibration system enables precise determination of rise time of photosensitive detectors. To perform a calibration, the time-voltage curve of the excitation voltage for a light source is compared with the time-voltage curve of the voltage output from a photosensitive detector which is responding to the light