Waveform synthesis of multi-frequency sinusoids with 2&lt;sup&gt;n&lt;/sup&gt;th primary harmonics based on Walsh functions

Yang, Yuxiang; Wang, Jian; Gao, Zhenzhong; Li, Dacheng; Wang, Jue

doi:10.1109/biocas.2009.5372066

Cited by 8 publications

(3 citation statements)

References 7 publications

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“…It leads to the idea of creating binary multifrequency signals, as proposed in [19]. We can also derive binary multifrequency signals by detecting zero crossings of multi-sine signal according to the following formula:…”

Section: Implementation Of Signal Processingmentioning

confidence: 99%

Front-end electronics for impedimetric microfluidic devices

et al. 2011

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Impedance spectroscopy is a common approach in assessing passive electrical properties of biological matter, however, serious problems appear in microfluidic devices in connection with distortion free signal acquisition from microelectrodes. The quality of impedance measurements highly depends on the presence of stray capacitances, signal distortions, and accompanying noises. Measurement deficiencies may be minimized with optimized electronics and sensing electrodes. The quality can further be improved with appropriate selection of measuring signals and also with selection of measuring methods such as a choice between current or voltage sources and between differential or singleended techniques. The microfluidic device that we present here incorporates an impedance sensor, which consists of an array of two sequential pairs of parallel microelectrodes, embedded in a microfluidic channel. All electronics and fluidic components are placed inside a metal holder, which ensures electric and fluidic connections to peripheral instruments. This configuration provides short electric connections and proper shielding. The method that we are using to evaluate the sample's impedance is the differential measurement technique, capable of suppressing the common mode signals and interferences, appearing in the signal-conditioning front-end circuit. Besides, it opens the possibility for compensating stray effects of the electrodes. For excitation we employ wideband signals, such as chirps or multifreqyency signals, which allow fast measurements, essential in the most impedimetric experiments in biology. The impedance spectra cover the frequency range between 10kHz -10MHz. This is essential for accessing information relating to β-dispersion, which characterizes the cell's structural properties. We present two measurement schemes: (i) an in-phase differential method, which employs two transimpedance amplifiers, and (ii) an anti-phase method, which uses one transimpedance amplifier. In this study we analyze and compare the sensitivity, signal-to-noise-ratio, and operational bandwidths of these two methods against other commonly used related circuits.

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Section: Implementation Of Signal Processingmentioning

confidence: 99%

Front-end electronics for impedimetric microfluidic devices

et al. 2011

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“…The authors previously proposed a method based on Walsh functions to synthesize multifrequency mixed (MFM) signal [ 22 , 23 ], which is a type of binary sequence with only +1 and −1 value and has majority of energy concentrated on its 2 n th primary harmonics. But the MFM signal has several drawbacks.…”

Section: Introductionmentioning

confidence: 99%

Development of a Stair-Step Multifrequency Synchronized Excitation Signal for Fast Bioimpedance Spectroscopy

Yang

Bian

et al. 2014

BioMed Research International

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Wideband excitation signal with finite prominent harmonic components is desirable for fast bioimpedance spectroscopy (BIS) measurements. This work introduces a simple method to synthesize and realize a type of periodical stair-step multifrequency synchronized (MFS) signal. The Fourier series analysis shows that the p-order MFS signal f(p, t) has constant 81.06% energy distributed equally on its p 2nth primary harmonics. The synthesis principle is described firstly and then two examples of the 4-order and 5-order MFS signals, f(4, t) and f(5, t), are synthesized. The method to implement the MFS waveform based on a field-programmable gate array (FPGA) and a digital to analog converter (DAC) is also presented. Both the number and the frequencies of the expected primary harmonics can be adjusted as needed. An impedance measurement experiment on a RC three-element equivalent model is performed, and results show acceptable precision, which validates the feasibility of the MFS excitation.

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“…The authors proposed a simple method to synthesize the MFM signal based on Walsh functions whose majority of energy is concentrated on the several expected 2 n th primary harmonics [20]. This communication describes the implementation of a wideband excitation source based on the MFM signal.…”

Section: Introductionmentioning

confidence: 99%

Design of a wideband excitation source for fast bioimpedance spectroscopy

Yang¹,

Kang²,

Lu³

et al. 2010

Meas. Sci. Technol.

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Multi-frequency-one-time (MFOT) measurement of bioimpedance spectroscopy (BIS) can greatly reduce measurement time and grasp the transient physiological status of a living body compared with the traditional one-frequency-one-time (OFOT) measurement technology, and a wideband excitation source mixed with multiple frequencies is a crucial part of MFOT measurement of BIS. This communication describes a design of a wideband excitation source. Firstly, a multi-frequency mixed (MFM) signal containing seven primary harmonics is synthesized based on Walsh functions, which is a periodical and rectangular signal and whose 68.9% of the energy is homogeneously distributed on its seven 2nth primary harmonics. Then the MFM signal is generated by a field programmable gate array (FPGA), and a unipolar-to-bipolar convertor (UBC) is designed to convert the unipolar signal into bipolar signal. Finally, the bipolar MFM signal is driven by a voltage-controlled current source (VCCS). A 2R-1C series model is adopted as the load of the VCCS, and the simulated voltage response on the load is obtained based on the theoretical analysis. Experiments show that the practical waveform on the load matches well with the theoretical analysis, which indicates that the VCCS has a good performance on the MFM signal. The design of the wideband excitation source establishes a good foundation for fast measurement of BIS.

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Waveform synthesis of multi-frequency sinusoids with 2<sup>n</sup>th primary harmonics based on Walsh functions

Cited by 8 publications

References 7 publications

Front-end electronics for impedimetric microfluidic devices

Front-end electronics for impedimetric microfluidic devices

Development of a Stair-Step Multifrequency Synchronized Excitation Signal for Fast Bioimpedance Spectroscopy

Design of a wideband excitation source for fast bioimpedance spectroscopy

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