Special Issue "Design and Application of Biomedical Circuits and Systems"

A special issue of Electronics (ISSN 2079-9292). This special issue belongs to the section "Bioelectronics".

Deadline for manuscript submissions: closed (31 August 2020).

Special Issue Editors

Prof. Dr. Alberto Yufera
Website
Guest Editor
Universidad de Sevilla, Instituto de Microelectronica de Sevilla (US/IMSE), Spain.
Interests: biomedical circuit applications based on bioimpedance; bio-sensors and microelectrodes; analysis and design of analog integrated circuits and systems for signal processing; CAD tools for analog circuits
Special Issues and Collections in MDPI journals
Prof. Dr. Gloria Huertas
Website
Guest Editor
Universidad de Sevilla, Instituto de Microelectronica de Sevilla (US/IMSE), Spain.
Interests: biomedical circuits and systems, bio-sensors, laboratory on-a-chip (LoC), bioimpedance, microelectrode, design for test.
Prof. Dr. Belen Calvo
Website
Guest Editor
Group of Electronic Design, Aragon Institute for Engineering Research (GDE-I3A), University of Zaragoza, Spain.
Interests: analog and mixed-mode CMOS IC design, low-voltage low-power monolithic sensor interfaces, smart instrumentation.

Special Issue Information

Dear Colleagues,

The development of new sensing technologies, biomaterials, microelectronic devices, microfluidic systems and micro-electro-mechanical systems (MEMs), etc., opens the window to new biomedical circuit and system opportunities to measure “better”, and also using “alternative” methods, to find relevant information for physician and biologist teams, with applications such as diagnosis, therapy, clinical testing and bio-signal monitoring. However, the accomplishment of new medical equipment for specific tests in the health field pose significant challenges in the electronic circuits and systems needed, whose performance is vital for proper and accurate data acquisition tasks.

This Special Issue is devoted mainly to incorporating proposals of bio-sensing signals based on new circuits and systems approaches. In general, it is focused on new bio-signal analog front-end (AFE) circuits; specific circuit development for known and new sensor/sensing approaches; circuits for biomedical signal processing; low-voltage and low-power circuits and their application to implantable and wearable devices; circuits and systems for clinical applications; circuits for sensing/actuation in MEM systems, Lab-on-a-Chip (LoC), micro-total-analysis Systems (uTAS); cell assays and manipulation, etc. The main topics of interest include, but are not limited to:

  • Analog front-end (AFE) circuits
  • Circuits for bioimpedance testing
  • Capacitive-based circuits
  • Circuits for new sensing devices and microelectrodes
  • ECG, EEG, EMG, EoG, etc., circuits and systems
  • Circuits for implantable and wearable devices
  • LP/LV circuits in biomedical environments
  • Micro-energy harvesting
  • Circuits and systems in clinical applications
  • Circuits for cell, DNA, bacteria, virus, etc., assays
  • Brain interfaces
  • Internet of things for remote healthcare

Prof. Dr. Alberto Yufera
Prof. Dr. Gloria Huertas
Prof. Dr. Belen Calvo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Electronics is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Analog front-end (AFE) circuits
  • Bioimpedance
  • Microelectrodes and MEAs
  • Biosensors
  • Lab-on-a-Chip (LoC)
  • ECG, EEG, EMG, EoG, etc., circuits and systems
  • Circuits for implantable and wearable devices
  • LP/LV circuits in biomedical environments
  • Micro-energy harvesting
  • Circuits and systems in clinical applications
  • Circuits for cell, DNA, bacteria, virus, etc., assays
  • Brain interfaces
  • Internet of things for remote healthcare

Published Papers (13 papers)

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Editorial

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Open AccessEditorial
Design and Application of Biomedical Circuits and Systems
Electronics 2020, 9(11), 1920; https://doi.org/10.3390/electronics9111920 - 15 Nov 2020
Abstract
The development of new sensing technologies, biomaterials, microelectronic devices, microfluidic systems and micro-electro-mechanical systems (MEMs) etc [...] Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)

Research

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Open AccessArticle
On the DC Offset Current Generated during Biphasic Stimulation: Experimental Study
Electronics 2020, 9(8), 1198; https://doi.org/10.3390/electronics9081198 - 25 Jul 2020
Cited by 1
Abstract
This paper deals with the DC offset currents generated by a platinum electrode matrix during biphasic stimulation. A fully automated test bench evaluates the nanoampere range DC offset currents in a realistic and comprehensive scenario by using platinum electrodes in a saline solution [...] Read more.
This paper deals with the DC offset currents generated by a platinum electrode matrix during biphasic stimulation. A fully automated test bench evaluates the nanoampere range DC offset currents in a realistic and comprehensive scenario by using platinum electrodes in a saline solution as a load for the stimulator. Measurements are performed on different stimulation patterns for single or dual hexagonal stimulation sites operating simultaneously and alternately. The effectiveness of the return electrode presence in reducing the DC offset current is considered. Experimental results show how for a defined nominal injected charge, the generated DC offset currents differ depending on the stimulation patterns, frequency, current amplitude, and pulse width of a biphasic signal. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessEditor’s ChoiceArticle
Multichannel Biphasic Muscle Stimulation System for Post Stroke Rehabilitation
Electronics 2020, 9(7), 1156; https://doi.org/10.3390/electronics9071156 - 17 Jul 2020
Cited by 2
Abstract
We present biphasic stimulator electronics developed for a wearable functional electrical stimulation system. The reported stimulator electronics consist of a twenty four channel biphasic stimulator. The stimulator circuitry is physically smaller per channel and offers a greater degree of control over stimulation parameters [...] Read more.
We present biphasic stimulator electronics developed for a wearable functional electrical stimulation system. The reported stimulator electronics consist of a twenty four channel biphasic stimulator. The stimulator circuitry is physically smaller per channel and offers a greater degree of control over stimulation parameters than existing functional electrical stimulator systems. The design achieves this by using, off the shelf multichannel high voltage switch integrated circuits combined with discrete current limiting and dc blocking circuitry for the frontend, and field programmable gate array based logic to manage pulse timing. The system has been tested on both healthy adults and those with reduced upper limb function following a stroke. Initial testing on healthy users has shown the stimulator can reliably generate specific target gestures such as palm opening or pointing with an average accuracy of better than 4 degrees across all gestures. Tests on stroke survivors produced some movement but this was limited by the mechanical movement available in those users’ hands. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessArticle
High-Performance Analog Front-End (AFE) for EOG Systems
Electronics 2020, 9(6), 970; https://doi.org/10.3390/electronics9060970 - 11 Jun 2020
Cited by 1
Abstract
Electrooculography is a technique for measuring the corneo-retinal standing potential of the human eye. The resulting signal is called the electrooculogram (EOG). The primary applications are in ophthalmological diagnosis and in recording eye movements to develop simple human–machine interfaces (HCI). The electronic circuits [...] Read more.
Electrooculography is a technique for measuring the corneo-retinal standing potential of the human eye. The resulting signal is called the electrooculogram (EOG). The primary applications are in ophthalmological diagnosis and in recording eye movements to develop simple human–machine interfaces (HCI). The electronic circuits for EOG signal conditioning are well known in the field of electronic instrumentation; however, the specific characteristics of the EOG signal make a careful electronic design necessary. This work is devoted to presenting the most important issues related to the design of an EOG analog front-end (AFE). In this respect, it is essential to analyze the possible sources of noise, interference, and motion artifacts and how to minimize their effects. Considering these issues, the complete design of an AFE for EOG systems is reported in this work. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessArticle
MEDUSA: A Low-Cost, 16-Channel Neuromodulation Platform with Arbitrary Waveform Generation
Electronics 2020, 9(5), 812; https://doi.org/10.3390/electronics9050812 - 15 May 2020
Cited by 1
Abstract
Neural stimulation systems are used to modulate electrically excitable tissue to interrogate neural circuit function or provide therapeutic benefit. Conventional stimulation systems are expensive and limited in functionality to standard stimulation waveforms, and they are bad for high frequency stimulation. We present MEDUSA, [...] Read more.
Neural stimulation systems are used to modulate electrically excitable tissue to interrogate neural circuit function or provide therapeutic benefit. Conventional stimulation systems are expensive and limited in functionality to standard stimulation waveforms, and they are bad for high frequency stimulation. We present MEDUSA, a system that enables new research applications that can leverage multi-channel, arbitrary stimulation waveforms. MEDUSA is low cost and uses commercially available components for widespread adoption. MEDUSA is comprised of a PC interface, an FPGA for precise timing control, and eight bipolar current sources that can each address up to 16 electrodes. The current sources have a resolution of 15.3 nA and can provide ±5 mA with ±5 V compliance. We demonstrate charge-balancing techniques in vitro using a custom microelectrode. An in vivo strength-duration curve for earthworm nerve activation is also constructed using MEDUSA. MEDUSA is a multi-functional neuroscience research tool for electroplating microelectrodes, performing electrical impedance spectroscopy, and examining novel neural stimulation protocols. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessFeature PaperArticle
FPGA-Based Doppler Frequency Estimator for Real-Time Velocimetry
Electronics 2020, 9(3), 456; https://doi.org/10.3390/electronics9030456 - 08 Mar 2020
Cited by 2
Abstract
In range-Doppler ultrasound applications, the velocity of a target can be measured by transmitting a mechanical wave, and by evaluating the Doppler shift present on the received echo. Unfortunately, detecting the Doppler shift from the received Doppler spectrum is not a trivial task, [...] Read more.
In range-Doppler ultrasound applications, the velocity of a target can be measured by transmitting a mechanical wave, and by evaluating the Doppler shift present on the received echo. Unfortunately, detecting the Doppler shift from the received Doppler spectrum is not a trivial task, and several complex estimators, with different features and performance, have been proposed in the literature for achieving this goal. In several real-time applications, hundreds of thousands of velocity estimates must be produced per second, and not all of the proposed estimators are capable of performing at these high rates. In these challenging conditions, the most widely used approaches are the full centroid frequency estimate or the simple localization of the position of the spectrum peak. The first is more accurate, but the latter features a very quick and straightforward implementation. In this work, we propose an alternative Doppler frequency estimator that merges the advantages of the aforementioned approaches. It exploits the spectrum peak to get an approximate position of the Doppler frequency. Then, centered in this position, a centroid search is applied on a reduced frequency interval to refine the estimate. Doppler simulations are used to compare the accuracy and precision performance of the proposed algorithm with respect to current state of the art approaches. Finally, a Field Programmable Gate Array (FPGA) implementation is proposed that is capable of producing more than 200 k low noise estimates per second, which is suitable for the most demanding real-time applications. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessArticle
An Interference Suppression Method for Non-Contact Bioelectric Acquisition
Electronics 2020, 9(2), 293; https://doi.org/10.3390/electronics9020293 - 08 Feb 2020
Cited by 3
Abstract
For non-contact bioelectrical acquisition, a new interference suppression method, named ‘noise neutralization method’, is proposed in this paper. Compared with the traditional capacitive driven-right-leg method, the proposed method is characterized with that there is an optimal gain to achieve the minimum interference output [...] Read more.
For non-contact bioelectrical acquisition, a new interference suppression method, named ‘noise neutralization method’, is proposed in this paper. Compared with the traditional capacitive driven-right-leg method, the proposed method is characterized with that there is an optimal gain to achieve the minimum interference output whatever for the electrode interface impedance mismatch caused by body motion and is more effective for smaller reference electrode areas. The performance of traditional capacitive driven-right-leg method is analyzed and the difficulty to suppress interference in the case of the interface impedance mismatch is pointed out. Therefore, a noise neutralization method is proposed by applying the reference electrode and a 50 Hz band-pass filter to obtain the interference of the human body and adapting the gains to neutralize the interference inputs of two acquisition electrodes and achieve the minimum interference output. The performance of the proposed method is theoretically analyzed and verified by the experiment results, which shows that the proposed method has similar performance to that of the traditional capacitive driven-right-leg method with electrode interface impedance match, while has better interference suppression ability with electrode interface impedance mismatch caused by body motion. It is suggested that the proposed method can be preferred in the case of limited reference electrode area or interface impedance mismatch. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessArticle
New RSA Encryption Mechanism Using One-Time Encryption Keys and Unpredictable Bio-Signal for Wireless Communication Devices
Electronics 2020, 9(2), 246; https://doi.org/10.3390/electronics9020246 - 02 Feb 2020
Cited by 2
Abstract
Applying the data encryption method used in conventional personal computers (PC) to wireless communication devices such as IoT is not trivial. Because IoT equipment is extremely slow in transferring data and has a small hardware area compared with PCs, it is difficult to [...] Read more.
Applying the data encryption method used in conventional personal computers (PC) to wireless communication devices such as IoT is not trivial. Because IoT equipment is extremely slow in transferring data and has a small hardware area compared with PCs, it is difficult to transfer large data and perform complicated operations. In particular, it is difficult to apply the RSA encryption method to wireless communication devices because it guarantees the stability of data encryption because it is difficult to factor extremely large prime numbers. Furthermore, it has become even more difficult to apply the RSA encryption method to IoT devices as a paper recently published indicated that it enables rapid fractional decomposition when using RSA encryption with a prime number generated through several pseudo-random number generators. To compensate for the disadvantages of RSA encryption, we propose a method that significantly reduces the encryption key using a true prime random number generator (TPRNG), which generates a prime number that cannot be predicted through bio-signals, and a disposable RSA encryption key. TPRNG has been verified by the National Institute of Standards and Technology. The NIST test and an RSA algorithm are implemented through Verilog. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessFeature PaperEditor’s ChoiceArticle
Development of a Compact, IoT-Enabled Electronic Nose for Breath Analysis
Electronics 2020, 9(1), 84; https://doi.org/10.3390/electronics9010084 - 01 Jan 2020
Cited by 6
Abstract
In this paper, we report on an in-house developed electronic nose (E-nose) for use with breath analysis. The unit consists of an array of 10 micro-electro-mechanical systems (MEMS) metal oxide (MOX) gas sensors produced by seven manufacturers. Breath sampling of end-tidal breath is [...] Read more.
In this paper, we report on an in-house developed electronic nose (E-nose) for use with breath analysis. The unit consists of an array of 10 micro-electro-mechanical systems (MEMS) metal oxide (MOX) gas sensors produced by seven manufacturers. Breath sampling of end-tidal breath is achieved using a heated sample tube, capable of monitoring sampling-related parameters, such as carbon dioxide (CO2), humidity, and temperature. A simple mobile app was developed to receive real-time data from the device, using Wi-Fi communication. The system has been tested using chemical standards and exhaled breath samples from healthy volunteers, before and after taking a peppermint capsule. Results from chemical testing indicate that we can separate chemical standards (acetone, isopropanol and 1-propanol) and different concentrations of isobutylene. The analysis of exhaled breath samples demonstrate that we can distinguish between pre- and post-consumption of peppermint capsules; area under the curve (AUC): 0.81, sensitivity: 0.83 (0.59–0.96), specificity: 0.72 (0.47–0.90), p-value: <0.001. The functionality of the developed device has been demonstrated with the testing of chemical standards and a simplified breath study using peppermint capsules. It is our intention to deploy this system in a UK hospital in an upcoming breath research study. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessArticle
A Computationally Efficient Mean Sound Speed Estimation Method Based on an Evaluation of Focusing Quality for Medical Ultrasound Imaging
Electronics 2019, 8(11), 1368; https://doi.org/10.3390/electronics8111368 - 18 Nov 2019
Cited by 1
Abstract
Generally, ultrasound receive beamformers calculate the focusing time delays of fixed sound speeds in human tissue (e.g., 1540 m/s). However, phase distortions occur due to variations of sound speeds in soft tissues, resulting in degradation of image quality. Thus, an optimal estimation of [...] Read more.
Generally, ultrasound receive beamformers calculate the focusing time delays of fixed sound speeds in human tissue (e.g., 1540 m/s). However, phase distortions occur due to variations of sound speeds in soft tissues, resulting in degradation of image quality. Thus, an optimal estimation of sound speed is required in order to improve image quality. Implementation of real-time sound speed estimation is challenging due to high computational and hardware complexities. In this paper, an optimal sound speed estimation method with a low-cost hardware resource is presented. In the proposed method, the optimal mean sound speed is determined by measuring the amplitude variance of pre-beamformed radio-frequency (RF) data. The proposed method was evaluated with phantom and in vivo experiments, and implemented on Virtex-4 with Xilinx ISE 12.4 using VHDL. Experiment results indicate that the proposed method could estimate the mean optimal sound speed and enhance spatial resolution with a negligible increase in the hardware resource usage. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessFeature PaperArticle
Incremental Low Rank Noise Reduction for Robust Infrared Tracking of Body Temperature during Medical Imaging
Electronics 2019, 8(11), 1301; https://doi.org/10.3390/electronics8111301 - 07 Nov 2019
Cited by 4
Abstract
Thermal imagery for monitoring of body temperature provides a powerful tool to decrease health risks (e.g., burning) for patients during medical imaging (e.g., magnetic resonance imaging). The presented approach discusses an experiment to simulate radiology conditions with infrared imaging along with an automatic [...] Read more.
Thermal imagery for monitoring of body temperature provides a powerful tool to decrease health risks (e.g., burning) for patients during medical imaging (e.g., magnetic resonance imaging). The presented approach discusses an experiment to simulate radiology conditions with infrared imaging along with an automatic thermal monitoring/tracking system. The thermal tracking system uses an incremental low-rank noise reduction applying incremental singular value decomposition (SVD) and applies color based clustering for initialization of the region of interest (ROI) boundary. Then a particle filter tracks the ROI(s) from the entire thermal stream (video sequence). The thermal database contains 15 subjects in two positions (i.e., sitting, and lying) in front of thermal camera. This dataset is created to verify the robustness of our method with respect to motion-artifacts and in presence of additive noise (2–20%—salt and pepper noise). The proposed approach was tested for the infrared images in the dataset and was able to successfully measure and track the ROI continuously (100% detecting and tracking the temperature of participants), and provided considerable robustness against noise (unchanged accuracy even in 20% additive noise), which shows promising performance. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Open AccessFeature PaperArticle
Soft Elbow Exoskeleton for Upper Limb Assistance Incorporating Dual Motor-Tendon Actuator
Electronics 2019, 8(10), 1184; https://doi.org/10.3390/electronics8101184 - 18 Oct 2019
Cited by 6
Abstract
Loss of muscle functions, such as the elbow, can affect the quality of life of a person. This research is aimed at developing an affordable two DOF soft elbow exoskeleton incorporating a dual motor-tendon actuator. The soft elbow exoskeleton can be used to [...] Read more.
Loss of muscle functions, such as the elbow, can affect the quality of life of a person. This research is aimed at developing an affordable two DOF soft elbow exoskeleton incorporating a dual motor-tendon actuator. The soft elbow exoskeleton can be used to assist two DOF motions of the upper limb, especially elbow and wrist movements. The exoskeleton is developed using fabric for the convenience purpose of the user. The dual motor-tendon actuator subsystem employs two DC motors coupled with lead-to-screw converting motion from angular into linear motion. The output is connected to the upper arm hook on the soft exoskeleton elbow. With this mechanism, the proposed actuator system is able to assist two DOF movements for flexion/extension and pronation/supination motion. Proportional-Integral (PI) control is implemented for controlling the motion. The optimized value of Kp and Ki are 200 and 20, respectively. Based on the test results, there is a slight steady-state error between the first and the second DC motor. When the exoskeleton is worn by a user, it gives more steady-state errors because of the load from the arm weight. The test results demonstrate that the proposed soft exoskeleton elbow can be worn easily and comfortably by a user to assist two DOF for elbow and wrist motion. The resulted range of motion (ROM) for elbow flexion–extension can be varied from 90° to 157°, whereas the maximum of ROM that can be achieved for pronation and supination movements are 19° and 18°, respectively. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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Review

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Open AccessFeature PaperReview
Insight on Electronic Travel Aids for Visually Impaired People: A Review on the Electromagnetic Technology
Electronics 2019, 8(11), 1281; https://doi.org/10.3390/electronics8111281 - 04 Nov 2019
Cited by 5
Abstract
This review deals with a comprehensive description of the available electromagnetic travel aids for visually impaired and blind people. This challenging task is considered as an outstanding research area due to the rapid growth in the number of people with visual impairments. For [...] Read more.
This review deals with a comprehensive description of the available electromagnetic travel aids for visually impaired and blind people. This challenging task is considered as an outstanding research area due to the rapid growth in the number of people with visual impairments. For decades, different technologies have been employed for solving the crucial challenge of improving the mobility of visually impaired people, but a suitable solution has not yet been developed. Focusing this contribution on the electromagnetic technology, the state-of-the-art of available solutions is demonstrated. Electronic travel aids based on electromagnetic technology have been identified as an emerging technology due to their high level of achievable performance in terms of accuracy, flexibility, lightness, and cost-effectiveness. Full article
(This article belongs to the Special Issue Design and Application of Biomedical Circuits and Systems)
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