A 296 nJ Energy-per-Measurement Relaxation Oscillator-Based Analog Front-End for Chemiresistive Sensors

Radogna, Antonio Vincenzo; Capone, S.; Francioso, Luca; Siciliano, P.; D'Amico, S.

doi:10.1109/tcsi.2020.3047508

Cited by 15 publications

(5 citation statements)

References 15 publications

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“…The sensor module hosts 6 commercial micro-electro-mechanical systems (MEMS) MOX-based gas sensors on SMD (surface-mount device) package. Thanks to the MEMS technology, the size and fabrication costs of sensors are significantly reduced and this leads to smaller and cheaper sensing devices [27]. In addition to the 6 SMD sensors, a pair of sockets for sensors in 4 pin through-hole TO-5 packages, was provided, with a final array configuration of 8 sensors.…”

Section: A System Overviewmentioning

confidence: 99%

“…The AFE section represents the interface between the MCU and the sensor module. The latter module mounts the MOXbased chemiresistive gas sensor array, whose working principle is based on electrical resistance changes of sensing layers in response to gases and volatiles [27]. As the sensor's resistance can vary over several decades [28], a circuit based on a multi-…”

Section: B Proposed Analog-front End (Afe) Circuit Designmentioning

confidence: 99%

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A Multi-matrix E-nose with Optimal Multi-ranged AFE Circuit for Human Volatilome Fingerprinting

Radogna,

Grassi,

D’Amico

et al. 2023

IEEE Sensors J.

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Since hundreds of volatile organic compounds (VOCs) produced by cell metabolism and released into the blood are excreted through exhaled breath or body fluids, the volatile composition (volatilome) of human samples reflects a subject's state of health and early signals any abnormal deviation from healthy to disease. The chemical volatilomic profile of biological matrices can be transduced in a digital fingerprint by low cost and easy-to-use electronic nose (e-nose) devices based on gas sensor arrays. The e-noses can be used to aid clinical diagnosis supporting conventional diagnostic methods that sometimes require expensive or invasive medical procedures and delays in diagnoses. In this paper, an e-nose devoted to the human volatilome fingerprinting is presented. The device, code-named SPYROX, adopts an array of 8 metal-oxide (MOX) gas sensors and it is able to analyze response signals from different matrices (multi-matrix samples), dealing with exhaled breath and headspace analysis of human biological samples. While other works in literature neglect the design of the interface circuit, here an optimal multi-ranged analog front-end (AFE) circuit is proposed. It aims to the optimization of the read-out sensitivity which, ultimately, leads to accurate training datasets and, consequently, to high classification scores. Finally, the efficacy of the device is proved by testing both chemical standards and mixtures. As a result, a classification accuracy of 100% is achieved with a linear discriminant model. The experimental results give a proof on the system's efficacy to the fingerprint analysis of complex gas mixtures, which are typical of human volatilome.

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Section: A System Overviewmentioning

confidence: 99%

Section: B Proposed Analog-front End (Afe) Circuit Designmentioning

confidence: 99%

A Multi-matrix E-nose with Optimal Multi-ranged AFE Circuit for Human Volatilome Fingerprinting

Radogna,

Grassi,

D’Amico

et al. 2023

IEEE Sensors J.

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“…The resulting signal is buffered by the CMP1 Schmitt trigger buffer (SN74LVC1G17, Texas Instruments) and, thus, fed in the analog circuit composed by OA1 and OA2 opamps, the M1 mosfet, the R L resistor, and the RC sensor model, made by the parallel of the R S resistor and the C S capacitor. The equivalent circuit of the sensor, made by R S and C S , has proven to model, at least in first approximation, the electrical behavior of resistive and capacitive sensors [24]- [28]. For example, in the case of metal-oxide (MOX) gas sensors, the R S value ranges from hundreds of to several M, whereas the C S assumes typically a value under 1 pF [24].…”

Section: A Analog Front-end (Afe)mentioning

confidence: 99%

“…The equivalent circuit of the sensor, made by R S and C S , has proven to model, at least in first approximation, the electrical behavior of resistive and capacitive sensors [24]- [28]. For example, in the case of metal-oxide (MOX) gas sensors, the R S value ranges from hundreds of to several M, whereas the C S assumes typically a value under 1 pF [24]. Given the supply voltage of the circuit, V D D , the voltage reference V D D /2 is generated through a precision voltage reference (REF2030, Texas Instruments).…”

Section: A Analog Front-end (Afe)mentioning

confidence: 99%

Performance Analysis of an MLS-Based Interface for Impulse Response Estimation of Resistive and Capacitive Sensors

Radogna

Capone

Francioso

et al. 2022

IEEE Trans. Circuits Syst. I

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This paper presents a performance analysis of a system for electrochemical impedance spectroscopy (EIS). The system, composed by an analog front-end (AFE) and a custom microcontroller (MCU) board, performs the impulse response (IR) measurement of linear and time-invariant (LTI) systems with pseudo-random excitation signals. As a novelty, a specific AFE for the interfacing of two-terminal resistive and capacitive sensors is covered in detail. The paper proposes, for the first time, a mathematical model to predict the impact of the main noise sources in the measured IR. Thanks to the proposed approach, the AFE and the system's parameters can be properly designed in order to reduce the error, thus, minimizing the energy-per-error figure of merit (FOM) as well. The AFE is realized as discrete-components circuit and it has been included in a custom MCU-based measurement system as an expansion module. The predicted results from the mathematical model, in terms of noise power, SNR, and measurement error are validated through system-level simulation and experimental measurements. The system performs the IR measurement with 1023 points, showing root-mean-square (RMS) measurement errors of 1% and 1.4% for the tested ADC sampling frequencies of 62.5 kHz and 125 kHz, respectively. These lead to excellent FOM values of 128.9 mJ • % 2 and 252.6 mJ • % 2 that outstand the state of the art.

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“…As an application example, the case of impedance spectroscopy of a metal-oxide (MOX) gas sensor could be considered for the ω T sizing. These sensors exhibit a typical parasitic capacitance, C S , of about 1 pF and a wide resistance value, R S , from a few kΩ to several MΩ [14]. For instance, assuming a typical resistance value of 160 kΩ, in order to achieve an error of 1% on the measured τ [5], it turns out from ( 14) that an opamp with a ω T greater than 100 MHz is needed.…”

Section: Analog Front End (Afe)mentioning

confidence: 99%

A 177 ppm RMS Error-Integrated Interface for Time-Based Impedance Spectroscopy of Sensors

et al. 2022

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This paper presents an integrated circuit for time-based electrical impedance spectroscopy (EIS) of sensors. The circuit exploits maximum-length sequences (MLS) in order to perform a broadband excitation of the sensors under test. Therefore, the measured time-domain EIS is obtained by cross-correlating the input with the output of the analog front end (AFE). Unlike the conventional digital approach, the cross-correlation operation is performed in the analog domain. This leads to a lower RMS error in the measured time-domain EIS since the signal processing is not affected by the quantization noise of the analog-to-digital converter (ADC). It also relaxes the sampling frequency of the ADC leading, along with the lack of random access memory (RAM) usage, to a reduced circuit complexity. Theoretical concepts about the circuit’s design and operation are presented, with an emphasis on the thermal noise phenomenon. The simulated performances are shown by testing a sensor’s equivalent model composed of a 50kΩ resistor in parallel with a 100pF capacitor. A time-based EIS output of 255 points was obtained with a maximum tested frequency of 500kHz and a simulated RMS error of 0.0177 (or 177 ppm).

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A 296 nJ Energy-per-Measurement Relaxation Oscillator-Based Analog Front-End for Chemiresistive Sensors

Cited by 15 publications

References 15 publications

A Multi-matrix E-nose with Optimal Multi-ranged AFE Circuit for Human Volatilome Fingerprinting

A Multi-matrix E-nose with Optimal Multi-ranged AFE Circuit for Human Volatilome Fingerprinting

Performance Analysis of an MLS-Based Interface for Impulse Response Estimation of Resistive and Capacitive Sensors

A 177 ppm RMS Error-Integrated Interface for Time-Based Impedance Spectroscopy of Sensors

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