An Evaluation Study of Various Excitation Signals for Electrical Impedance Spectroscopy

Rajabzadeh, Mahdi; Ungethuem, Jonathan; Mandry, Holger; Schilpp, Carolin; Wittekindt, Oliver H.; Ortmanns, Maurits

doi:10.1109/iscas.2019.8702178

Cited by 12 publications

(8 citation statements)

References 11 publications

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“…For achieving high linearity with a DAC alone, DAC-based sinusoids typically require high N DAC and OSR, increasing the hardware complexity and limiting the maximum f SG , respectively. Adopting a DSM in on-chip SSGs can reduce N DAC and ease the filter requirements [38], [66]- [69]. However, they still need a high OSR.…”

Section: Discussionmentioning

confidence: 99%

“…The shaped out-band noise can be more easily filtered out by an LPF. While an EIS system adopting a single-bit DSM without an explicit LPF is verified using external instruments and board-level design [68], [69], on-chip SSGs based on DSM typically include an LPF to achieve high linearity [38], [66], [67]. A simple RC LPF [66] and a 2nd-order g m -C LPF [38] are adopted for attenuating the fast-moving out-band noises, finally generating a cleaner sinusoidal signal.…”

Section: A Dac-based Sinusoidmentioning

confidence: 99%

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On-Chip Sinusoidal Signal Generators for Electrical Impedance Spectroscopy: Methodological Review

Kweon¹,

Rafi

Cheon

et al. 2022

IEEE Trans. Biomed. Circuits Syst.

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This paper reviews architectures and circuit implementations of on-chip sinusoidal signal generators (SSGs) for electrical impedance spectroscopy (EIS) applications. In recent years, there have been increasing interests in on-chip EIS systems, which measure a target material's impedance spectrum over a frequency range. The on-chip implementation allows EIS systems to have low power and small form factor, enabling various biomedical applications. One of the key building blocks of on-chip EIS systems is on-chip SSG, which determines the frequency range and the analysis precision of the whole EIS system. On-chip SSGs are generally required to have high linearity, wide frequency range, and high power and area efficiency. They are typically composed of three stages in general: waveform generation, linearity enhancement, and current injection. First, a sinusoidal waveform should be generated in SSGs. The generated waveform's frequency should be accurately adjustable over a wide range. The firstly generated waveform may not be perfectly linear, including unwanted harmonics. In the following linearity-enhancement step, these harmonics are attenuated by using filters typically. As the linearity of the waveform is improved, the precision of the EIS system gets ensured. Lastly, the filtered voltage waveform is now converted to a current by a current driver. Then, the current sinusoidal signal is injected into the target impedance. This review discusses the principles, advantages, and disadvantages of various techniques applied to each step in state-of-the-art on-chip SSGs. In addition, state-of-the-art designs are compared and summarized.

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Section: Discussionmentioning

confidence: 99%

Section: A Dac-based Sinusoidmentioning

confidence: 99%

On-Chip Sinusoidal Signal Generators for Electrical Impedance Spectroscopy: Methodological Review

Kweon¹,

Rafi

Cheon

et al. 2022

IEEE Trans. Biomed. Circuits Syst.

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“…To avoid this issue as illustrated in Fig. 2 a current-output 12-bit DAC is utilized and then the output current is converted to voltage domain with usage a power amplifier, which can drive more than 300 mA output current [6]. The drivability of the output is very important since at high frequency excitation, it is expected to see few ohms impedance, which require the excitation signal to provide more than ≈ 50 mA of currents for the 24 wells.…”

Section: B Excitation Partmentioning

confidence: 99%

“…In the EIS measurements, the user can specify the frequency range of interest and in the CV mode, the maximum and minimum voltage and the speed of the ramps. In order to achieve higher SNR, a digital lock-in technique can be used due to the known excitation frequency [5], [6]. In order to have a good trade-off between SNR and measurement time, an over sampling factor of 10 has been used.…”

Section: Processing Unitmentioning

confidence: 99%

A 24-Ch. Multi-Electrode Array Allowing Fast EIS to Determine Transepithelial Electrical Resistance

Rajabzadeh

Ungethuem

Herkle

et al. 2019

2019 IEEE Biomedical Circuits and Systems Conference (BioCAS)

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Electrochemical Impedance Spectroscopy (EIS) is a standard method to investigate properties of biological samples due to its non-invasiveness. Multi-electrode arrays (MEA) perform parallel measurements, which lead to higher throughput and thus reduced measurement time. However, implementing a parallel MEA EIS needs considerations to achieve safe and fast measurements. Commercially available devices perform single EIS and then serially scan the MEA. Their limited frequency range and limited detection impedance can be further increased to support more application. This work presents a 24 channel MEA EIS system that has highly reduced measurement time in comparison to commercially available solutions by utilizing multitone excitation signals. The EIS system has been implemented on a two layer PCB and successfully tested with biological samples. It consumes 17.5 × 17.5 cm 2 and draws 300 mA from a 5 V supply voltage. The EIS measurement frequency range spans from 10 mHz to 100 kHz and can detect impedances from 6 Ω to 300 kΩ. The prototype measurements have been compared with the commercially available devices and showed matching better than 95%.

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“…In portable applications, especially in real-time monitoring, the time and power required to make a single measurement are crucial. The measurement time depends on the lowest excited frequency point but also on the used IS technique [13]- [16]. From this standpoint, wideband IS is preferable to narrowband IS [14], [17], and pseudo-random-binary-sequence (PRBS)-based IS deserves special attention because of its straightforward implementation.…”

Section: Introductionmentioning

confidence: 99%

Energy-Efficient PRBS Impedance Spectroscopy on a Digital Versatile Platform

Luciani

Crescentini

Romani

et al. 2021

IEEE Trans. Instrum. Meas.

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This paper presents the digital design of a versatile and low-power broadband impedance spectroscopy (IS) system based on pseudo-random binary sequence (PRBS) excitation. The PRBS technique allows fast, and low-power estimation of the impedance spectrum over a wide bandwidth with adequate accuracy, proving to be a good candidate for portable medical devices, especially. This paper covers the low-power design of the firmware algorithms and implements them on a versatile and reconfigurable digital platform that can be easily adjusted to the specific application. It will analyze the digital platform with the aim of reducing power consumption while maintaining adequate accuracy of the estimated spectrum. The paper studies two main algorithms (time-domain and frequency-domain) used for PRBSbased IS and implements both of them on the ultra-low-power GAP-8 digital platform. They are compared in terms of accuracy, measurement time, and power budget, while general design tradeoffs are drawn out. The time-domain algorithm demonstrated the best accuracy while the frequency-domain one contributes more to save power and energy. However, analysis of the energy-per-error FOM revealed that the time-domain algorithm outperforms the frequency-domain algorithm offering better accuracy for the same energy consumption. Numerical methods and microprocessor resources are exploited to optimize the implementation of both algorithms achieving 27 ms in processing time, power consumption as low as 1.4 mW and a minimum energy consumption per measurement of 0.5 mJ, for a dense impedance spectrum estimation of 214 points.

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An Evaluation Study of Various Excitation Signals for Electrical Impedance Spectroscopy

Cited by 12 publications

References 11 publications

On-Chip Sinusoidal Signal Generators for Electrical Impedance Spectroscopy: Methodological Review

On-Chip Sinusoidal Signal Generators for Electrical Impedance Spectroscopy: Methodological Review

A 24-Ch. Multi-Electrode Array Allowing Fast EIS to Determine Transepithelial Electrical Resistance

Energy-Efficient PRBS Impedance Spectroscopy on a Digital Versatile Platform

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