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Design and Application of Biomedical Circuits and Systems

Authors:
Alberto Yufera at Universidad de Sevilla
Alberto Yufera
Gloria Huertas at Universidad de Sevilla
Gloria Huertas
Belén Calvo at University of Zaragoza
Belén Calvo
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Abstract

The development of new sensing technologies, biomaterials, microelectronic devices, microfluidic systems and micro-electro-mechanical systems (MEMs) etc [...]
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electronics
Editorial
Design and Application of Biomedical Circuits
and Systems
Alberto Yúfera 1, * , Gloria Huertas 1and Belen Calvo 2
1Instituto de Microelectrónica de Sevilla (IMSE-CSIC), Universidad de Sevilla, Av. Americo Vespuccio 24,
41092 Sevilla, Spain; gloria@imse-cnm.csic.es
2Grupo de Diseño Electrónico, Instituto de Investigación en Ingeniería de Aragón (GDE-I3A),
Universidad de Zaragoza, 50009 Zaragoza, Spain; becalvo@unizar.es
*Correspondence: yufera@imse-cnm.csic.es
Received: 5 November 2020; Accepted: 9 November 2020; Published: 15 November 2020
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1. Introduction
The development of new sensing technologies, biomaterials, microelectronic devices, microfluidic
systems and micro-electro-mechanical systems (MEMs) etc., opens the window to new biomedical
circuits and system opportunities to measure “better”, and to develop “alternative” methods to find
relevant information for physician and biologist teams, in applications such as diagnosis, therapy,
clinical tests and bio-signal monitoring. However, the accomplishment of new medical equipment
for specific tests in the health field poses significant challenges regarding the electronic circuits and
systems needed, whose performance is vital for proper and accurate data acquisition tasks.
2. Design and Application of Biomedical Circuits and Systems
This Special Issue is devoted mainly to incorporating proposals of bio-sensing signals based on
new circuits and system approaches. In general, it is focused on new bio-signal analog front-end (AFE)
circuits; the development of specific circuits for known and new sensor/sensing approaches; circuits
for biomedical signal processing; low-voltage and low-power (LV/LP) circuits and its 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. Main topics of interest are well described by the Special Issue keywords (but
not limited to):
•Analog front-end (AFE) circuits;
•Circuits for bioimpedance test;
•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 cells, DNA, bacteria, viruses etc. assays;
•Brain interfaces;
•Internet of Things for remote healthcare;
In the present Special Issue, twelve papers have been successfully incorporated. We hope you
enjoy reading this Special Issue and are inspired to address the technological challenges to help the
Electronics 2020,9, 1920; doi:10.3390/electronics9111920 www.mdpi.com/journal/electronics
Electronics 2020,9, 1920 2 of 3
medical industry and biologists to increase the human quality of life, which is the main objective.
These are the contribution papers:
1. On the DC Offset Current Generated during Biphasic Stimulation: Experimental Study [1].
2. Multichannel Biphasic Muscle Stimulation System for Post Stroke Rehabilitation [2].
3. High-Performance Analog Front-End (AFE) for EOG Systems [3].
4.
MEDUSA: A Low-Cost, 16-Channel Neuromodulation Platform with Arbitrary Waveform
Generation [4].
5. FPGA-Based Doppler Frequency Estimator for Real-Time Velocimetry [5].
6. An Interference Suppression Method for Non-Contact Bioelectric Acquisition [6].
7.
New RSA Encryption Mechanism Using One-Time Encryption Keys and Unpredictable Bio-Signal
for Wireless Communication Devices [7].
8. Development of a Compact, IoT-Enabled Electronic Nose for Breath Analysis [8].
9.
A Computationally Efficient Mean Sound Speed Estimation Method Based on an Evaluation of
Focusing Quality for Medical Ultrasound Imaging [9].
10. Incremental Low Rank Noise Reduction for Robust Infrared Tracking of Body Temperature during
Medical Imaging [10].
11.
Soft Elbow Exoskeleton for Upper Limb Assistance Incorporating Dual Motor-Tendon
Actuator [11].
12.
Insight on Electronic Travel Aids for Visually Impaired People: A Review on the Electromagnetic
Technology [12].
We are conscious about the very wide scope of biomedical circuits and systems applications,
and that our contribution it is only a grain of sand more, but we expect to be it useful for knowledge
progress in the field.
3. Conclusions
Biomedical engineering is today one of the most important research fields in the world. This fact
is parallel with the health challenges surrounding the improvement of human health as one of the main
vehicles to increase the quality of life. The maturity of many technologies, such as microelectronic,
biomaterial, microfluidic, together with progress in the biology and medicine fields, develop alternative
solutions for medical evaluation, diagnosis, therapy and research in general, opening the opportunity
for new medical devices, e.g., lab-on-a-chip, wearable technology, and implants. The biomedical
electronic industry supports the development of many of these new devices, as the main technologies
for bio-signal acquisition, processing, and communication. In this Special Issue contribution, we
present some significant contributions for biomedical applications, which, of course, should be fulfilled
and improved by future contributions.
Author Contributions:
Conceptualization, A.Y., G.H. and B.C.; methodology, A.Y., G.H. and B.C.; writing—review
and editing and project administration, A.Y., G.H. and B.C. All authors have read and agreed to the published
version of the manuscript.
Funding: This research received no external funding.
Conflicts of Interest: The authors declare no conflict of interest.
References
1.
Aiello, O. On the DC Offset Current Generated during Biphasic Stimulation: Experimental Study. Electronics
2020,9, 1198. [CrossRef]
2.
Ward, T.; Grabham, N.; Freeman, C.; Wei, Y.; Hughes, A.-M.; Power, C.; Tudor, J.; Yang, K. Multichannel
Biphasic Muscle Stimulation System for Post Stroke Rehabilitation. Electronics 2020,9, 1156. [CrossRef]
3.
L
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Electronics 2020,9, 970. [CrossRef]
Electronics 2020,9, 1920 3 of 3
4.
Tala, F.; Johnson, B.C. MEDUSA: A Low-Cost, 16-Channel Neuromodulation Platform with Arbitrary
Waveform Generation. Electronics 2020,9, 812. [CrossRef]
5.
Ricci, S.; Meacci, V. FPGA-Based Doppler Frequency Estimator for Real-Time Velocimetry. Electronics
2020
,
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Tang, Y.; Chang, R.; Zhang, L.; Yan, F. An Interference Suppression Method for Non-Contact Bioelectric
Acquisition. Electronics 2020,9, 293. [CrossRef]
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Yu, H.; Kim, Y. New RSA Encryption Mechanism Using One-Time Encryption Keys and Unpredictable
Bio-Signal for Wireless Communication Devices. Electronics 2020,9, 246. [CrossRef]
8.
Tiele, A.; Wicaksono, A.; Ayyala, S.K.; Covington, J.A. Development of a Compact, IoT-Enabled Electronic
Nose for Breath Analysis. Electronics 2020,9, 84. [CrossRef]
9.
Lee, J.; Yoo, Y.; Yoon, C.; Song, T.-k. A Computationally Efficient Mean Sound Speed Estimation Method
Based on an Evaluation of Focusing Quality for Medical Ultrasound Imaging. Electronics
2019
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[CrossRef]
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Yousefi, B.; Sharifipour, H.M.; Eskandari, M.; Ibarra-Castanedo, C.; Laurendeau, D.; Watts, R.; Klein, M.;
Maldague, X.P.V. Incremental Low Rank Noise Reduction for Robust Infrared Tracking of Body Temperature
during Medical Imaging. Electronics 2019,8, 1301. [CrossRef]
11.
Ismail, R.; Ariyanto, M.; Perkasa, I.A.; Adirianto, R.; Putri, F.T.; Glowacz, A.; Caesarendra, W. Soft Elbow
Exoskeleton for Upper Limb Assistance Incorporating Dual Motor-Tendon Actuator. Electronics
2019
,8, 1184.
[CrossRef]
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Cardillo, E.; Caddemi, A. Insight on Electronic Travel Aids for Visually Impaired People: A Review on the
Electromagnetic Technology. Electronics 2019,8, 1281. [CrossRef]
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MDPI stays neutral with regard to jurisdictional claims in published maps and institutional
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2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
ResearchGate has not been able to resolve any citations for this publication.
On the DC Offset Current Generated during Biphasic Stimulation: Experimental Study
Article
Full-text available
  • Jul 2020
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.
View
Multichannel Biphasic Muscle Stimulation System for Post Stroke Rehabilitation
Article
Full-text available
  • Jul 2020
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.
View
High-performance analog front-end (AFE) for EOG systems
Article
Full-text available
  • Jun 2020
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.
View
MEDUSA: A Low-Cost, 16-Channel Neuromodulation Platform with Arbitrary Waveform Generation
Article
Full-text available
  • May 2020
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.
View
FPGA-Based Doppler Frequency Estimator for Real-Time Velocimetry
Article
Full-text available
  • Mar 2020
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.
View
An Interference Suppression Method for Non-Contact Bioelectric Acquisition
Article
Full-text available
  • Feb 2020
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.
View
New RSA Encryption Mechanism Using One-Time Encryption Keys and Unpredictable Bio-Signal for Wireless Communication Devices
Article
Full-text available
  • Feb 2020
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.
View
Development of a Compact, IoT-Enabled Electronic Nose for Breath Analysis
Article
Full-text available
  • Jan 2020
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.
View
Insight on Electronic Travel Aids for Visually Impaired People: A Review on the Electromagnetic Technology
Article
Full-text available
  • Nov 2019
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.
View
A Computationally Efficient Mean Sound Speed Estimation Method Based on an Evaluation of Focusing Quality for Medical Ultrasound Imaging
Article
Full-text available
  • Nov 2019
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.
View