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Selected Papers from the 8th International Electronic Conference on Sensors and Applications

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A special issue of Sensors (ISSN 1424-8220).

Deadline for manuscript submissions: closed (30 September 2022) | Viewed by 24934

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Dr. Stefano Mariani

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Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy
Interests: MEMS; smart materials; micromechanics; machine learning-driven materials modeling
Special Issues, Collections and Topics in MDPI journals

Dr. Alberto Vallan

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Politecnico di Torino, Department of Electronics and Telecommunications, corso Duca degli Abruzzi, 24, I-10129 Torino, Italy
Interests: measurement instruments; sensors; optical fiber sensors; plastic optical fibers
Special Issues, Collections and Topics in MDPI journals

Dr. Stefan Bosse

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Department of Computer Science, University of Bremen, and Faculty Computer Science, University of Koblenz-Landau, Mainz, Germany
Interests: artificial intelligence; machine learning; distributed systems; parallel systems; programming languages; self-organizing systems; multi-agent systems
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue is going to comprise extended and expanded versions of proceedings papers from the 8th International Electronic Conference on Sensors and Applications, to be held 1–15 November 2021, on sciforum.net. In this 8th edition of the e-conference, contributors are invited to provide papers and presentations from the field of sensors and applications at large. Selected papers that will attract the most interest on the web, or that will provide a particularly innovative contribution, are going to be gathered for publication. These papers will be subjected to peer review and published with the aim of rapid and wide dissemination of research results, developments, and applications. We hope that this conference series will grow further in the future and become recognized as a new way and venue by which to (electronically) present new developments related to the field of sensors and their applications.

Dr. Stefano Mariani
Dr. Alberto Vallan
Dr. Stefan Bosse
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 submissions that pass pre-check are 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. Sensors 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 2600 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

Biosensors
Chemical sensors
Physical sensors
Sensor networks
Applications
Smart cities
Structural health monitoring technologies and sensor networks
Wearable sensors
Optical sensors
Sensing and imaging
Vehicular sensing
Positioning and navigation
Sensing for robotics and automation

Published Papers (9 papers)

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Research

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16 pages, 19992 KiB

Open AccessArticle

3D-Printable Piezoelectric Composite Sensors for Acoustically Adapted Guided Ultrasonic Wave Detection

by Thomas Roloff, Rytis Mitkus, Jann Niklas Lion and Michael Sinapius

Sensors 2022, 22(18), 6964; https://doi.org/10.3390/s22186964 - 14 Sep 2022

Cited by 4 | Viewed by 1684

Abstract

Commercially available photopolymer resins can be combined with lead zirconate titanate (PZT) micrometer size piezoelectric particles to form 3D-printable suspensions that solidify under UV light. This in turn makes it possible to realize various non-standard sensor geometries which might bring benefits, such as increased piezoelectric output in specific conditions and less interference with incoming waves due to better acoustical adaptation compared to solid PZT ceramics. However, it is unclear whether piezoelectric composite materials are suitable for guided ultrasonic wave (GUW) detection, which is crucial for structural health monitoring (SHM) in different applications. In this study, thin piezoelectric composite sensors are tape casted, solidified under UV light, covered with electrodes, polarized in a high electric field and adhesively bonded onto an isotropic aluminum waveguide. This approach helps to demonstrate the capabilities of tape casting’s freedom to manufacture geometrically differently shaped, thin piezoelectric composite sensors for GUW detection. In an experimental study, thin two-dimensional piezoelectric composite sensors demonstrate successful detection of GUW for frequency-thickness products of up to 0.5 MHz mm. An analytical calculation of the maximum and minimum amplitudes for the ratio of the wavelength and the sensor length in wave propagation direction shows good agreement with the sensor-recorded signals. The output of the piezoelectric composite sensors and occurring reflections as measure for wave interactions are compared to commercial piezoelectric discs to evaluate their performance. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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11 pages, 14490 KiB

Open AccessArticle

MEMS Vibrometer for Structural Health Monitoring Using Guided Ultrasonic Waves

by Jan Niklas Haus, Walter Lang, Thomas Roloff, Liv Rittmeier, Sarah Bornemann, Michael Sinapius and Andreas Dietzel

Sensors 2022, 22(14), 5368; https://doi.org/10.3390/s22145368 - 19 Jul 2022

Cited by 5 | Viewed by 2466

Abstract

Structural health monitoring of lightweight constructions made of composite materials can be performed using guided ultrasonic waves. If modern fiber metal laminates are used, this requires integrated sensors that can record the inner displacement oscillations caused by the propagating guided ultrasonic waves. Therefore, we developed a robust MEMS vibrometer that can be integrated while maintaining the structural and functional compliance of the laminate. This vibrometer is directly sensitive to the high-frequency displacements from structure-borne ultrasound when excited in a frequency range between its first and second eigenfrequency. The vibrometer is mostly realized by processes earlier developed for a pressure sensor but with additional femtosecond laser ablation and encapsulation. The piezoresistive transducer, made from silicon, is encapsulated between top and bottom glass lids. The eigenfrequencies are experimentally determined using an optical micro vibrometer setup. The MEMS vibrometer functionality and usability for structural health monitoring are demonstrated on a customized test rig by recording application-relevant guided ultrasonic wave packages with a central frequency of 100 kHz at a distance of 0.2 m from the exciting ultrasound transducer. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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14 pages, 1619 KiB

Open AccessArticle

A Simple Optical Sensor Based on Multimodal Interference Superimposed on Additive Manufacturing for Diameter Measurement

by Victor H. R. Cardoso, Paulo Caldas, Maria Thereza R. Giraldi, Cindy Stella Fernandes, Orlando Frazão, João C. W. Albuquerque Costa and José Luís Santos

Sensors 2022, 22(12), 4560; https://doi.org/10.3390/s22124560 - 17 Jun 2022

Cited by 5 | Viewed by 2158

Abstract

In many areas, the analysis of a cylindrical structure is necessary, and a form to analyze it is by evaluating the diameter changes. Some areas can be cited: pipelines for oil or gas distribution and radial growth of trees whose diameter changes are directly related to irrigation and the radial expansion since it depends on the water soil deficit. For some species, these radial variations can change in around 5 mm. This paper proposes and experimentally investigates a sensor based on a core diameter mismatch technique for diameter changes measurement. The sensor structure is a combination of a cylindrical piece developed using a 3D printer and a Mach–Zehnder interferometer. The pieces were developed to assist in monitoring the diameter variation. It is formed by splicing an uncoated short section of MMF (Multimode Fiber) between two standard SMFs (Singlemode Fibers) called SMF-MMF-SMF (SMS), where the MMF length is 15 mm. The work is divided into two main parts. Firstly, the sensor was fixed at two points on the first developed piece, and the diameter reduction caused dips or peaks shift of the transmittance spectrum due to curvature and strain influence. The fixation point (FP) distances used are: 5 mm, 10 mm, and 15 mm. Finally, the setup with the best sensitivity was chosen, from first results, to develop another test with an optimization. This optimization is performed in the printed piece where two supports are created so that only the strain influences the sensor. The results showed good sensitivity, reasonable dynamic range, and easy setup reproduction. Therefore, the sensor could be used for diameter variation measurement for proposed applications. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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14 pages, 2684 KiB

Open AccessArticle

Considerations and Limits of Embedding Sensor Nodes for Structural Health Monitoring into Fiber Metal Laminates

by Sarah Bornemann and Walter Lang

Sensors 2022, 22(12), 4511; https://doi.org/10.3390/s22124511 - 14 Jun 2022

Cited by 1 | Viewed by 1941

Abstract

The objective of this article is to present the results of our investigations concerning the environmental conditions that can be expected during the embedding process into fibre metal laminates and the consequences for a sensor node for structural health monitoring. The idea behind this investigation is to determine for which manufacturing conditions the integration of sensor nodes into the material can be done and to identify limits for this. The sensor nodes consist of commercially available integrated circuits and passive components soldered onto an adhesive-less flexible printed circuit board. They are tested under conditions above their specified limits, to find out if they are still working reliably after experiencing 155 min of 180

^{\circ} C

and 7 bar of pressure. Apart from occurring temperature damage, the effect of surrounding fibres potentially pushing away the components under the amount of pressure of the manufacturing process, as well as the potential of shorts due to conductive fibers are investigated and suitable solutions to prevent this are evaluated. One experiment exceeding the typical requirements of a fiber metal laminate embedding process for structural components will be conducted at 250

^{\circ} C

for 10 h, in order to determine the limits of embedding electronic sensor nodes. This time and temperature combination is expected to cause irreversible damage to the electronic system. Results show that it is possible to integrate electronics into materials under conditions far above their specifications when precautions are taken but also that there are limits that must not be exceeded during the embedding process. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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13 pages, 3368 KiB

Open AccessArticle

Design of Dust-Filtering Algorithms for LiDAR Sensors Using Intensity and Range Information in Off-Road Vehicles

by Ali Afzalaghaeinaeini, Jaho Seo, Dongwook Lee and Hanmin Lee

Sensors 2022, 22(11), 4051; https://doi.org/10.3390/s22114051 - 27 May 2022

Cited by 5 | Viewed by 4779

Abstract

Although the LiDAR sensor provides high-resolution point cloud data, its performance degrades when exposed to dust environments, which may cause a failure in perception for robotics applications. To address this issue, our study designed an intensity-based filter that can remove dust particles from LiDAR data in two steps. In the first step, it identifies potential points that are likely to be dust by using intensity information. The second step involves analyzing the point density around selected points and removing them if they do not meet the threshold criterion. To test the proposed filter, we collected experimental data sets under the existence of dust and manually labeled them. Using these data, the de-dusting performance of the designed filter was evaluated and compared to several types of conventional filters. The proposed filter outperforms the conventional ones in achieving the best performance with the highest F1 score and removing dust without sacrificing the original surrounding data. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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21 pages, 5424 KiB

Open AccessArticle

Comparison of Three Prototypes of PPG Sensors for Continual Real-Time Measurement in Weak Magnetic Field

by Jiří Přibil, Anna Přibilová and Ivan Frollo

Sensors 2022, 22(10), 3769; https://doi.org/10.3390/s22103769 - 16 May 2022

Cited by 5 | Viewed by 2484

Abstract

This paper is focused on investigation of three developed prototypes of sensors based on the photoplethysmography (PPG) principle for continual measurement of the PPG signal in the magnetic field environment with the inherent radiofrequency and electromagnetic disturbance. The tested prototypes differ in the used optical part of the PPG sensor and their working mode, control unit, power supply, and applied Bluetooth (BT) communication methods. The main aim of the current work was motivated by finding suitable and universal parameter settings for PPG signal real-time recording in different working mode conditions. Comparative measurements in laboratory conditions by certified commercial pulse oximeter and blood pressure monitor (BPM) devices show good stability and proper accuracy of finally determined heart rate values. The supplementary investigation certifies the necessity of the placement of the pressure cuff of the BPM device on the opposite arm than the tested PPG sensor. Measurement experiments inside the scanning area of the running weak field magnetic resonance scanner verify proper function and practical usability of sensed PPG signals for further processing and analysis in all three prototype cases. Additional testing shows that the BT transmission in the scanning area has no visible influence on the quality of the finally obtained scanner images. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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13 pages, 9806 KiB

Open AccessArticle

Displacement Sensing of an Active String Actuator Using a Step-Index Multimode Optical Fiber Sensor

by Weihang Tian, Shuichi Wakimoto, Takefumi Kanda and Daisuke Yamaguchi

Sensors 2022, 22(9), 3232; https://doi.org/10.3390/s22093232 - 22 Apr 2022

Cited by 1 | Viewed by 1925

Abstract

A thin McKibben artificial muscle is a pneumatic actuator with an outer diameter of only 1.8 mm. We fabricated a string-shaped actuator called an “active string actuator,” which achieves a high contractile displacement by accumulating thin McKibben artificial muscles. To control the displacement, the length of the active string actuator should be estimated. However, this is difficult because bulky and rigid sensors are unsuitable for the sensor element of the active string actuator. Therefore, in this study, we propose a new sensing method for estimating the length of an active string actuator. The proposed sensing system is simple and comprises only three components: a step-index multimode optical fiber, a light emitter, and a light receiver. A step-index multimode optical fiber was combined with the active string actuator, and the length was estimated from the change in the amount of light propagating in the optical fiber when the active string actuator was driven. Fundamental experiments were conducted in this study, and the results demonstrated that the optical fiber sensor value changed with the actuator length. This suggests that it is possible to estimate the displacement of an active string actuator using an optical fiber sensor. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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11 pages, 3240 KiB

Open AccessArticle

Spectral Fingerprint Investigation in the near Infra-Red to Distinguish Harmful Ethylene Glycol from Isopropanol in a Microchannel

by Elisabetta Bodo, Sabina Merlo and Valentina Bello

Sensors 2022, 22(2), 459; https://doi.org/10.3390/s22020459 - 08 Jan 2022

Viewed by 2058

Abstract

Ethylene glycol (EG) and isopropanol (ISO) are among the major toxic alcohols that pose a risk to human health. However, it is important to distinguish them, since EG is more prone to cause renal failure, and can thus be more dangerous when ingested than ISO. Analysis of alcohols such as isopropanol and ethylene glycol generally can be performed with a complex chromatographic method. Here, we present an optical method based on absorption spectroscopy, performed remotely on EG-ISO mixtures filling a microchannel. Mixtures of ethylene glycol in isopropanol at different volume concentrations were analyzed in a contactless manner in a rectangular-section glass micro-capillary provided with integrated reflectors. Fiber-coupled broadband light in the wavelength range 1.3–1.7 µm crossed the microchannel multiple times before being directed towards an optical spectrum analyzer. The induced zig-zag path increased the fluid–light interaction length and enhanced the effect of optical absorption. A sophisticated theoretical model was developed and the results of our simulations were in very good agreement with the results of the experimental spectral measurements. Moreover, from the acquired data, we retrieved a responsivity parameter, defined as power ratio at two wavelengths, that is linearly related to the EG concentration in the alcoholic mixtures. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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Review

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20 pages, 4764 KiB

Open AccessReview

Commercial Off-the-Shelf Components (COTS) in Realizing Miniature Implantable Wireless Medical Devices: A Review

by Sadeque Reza Khan, Andrew J. Mugisha, Andreas Tsiamis and Srinjoy Mitra

Sensors 2022, 22(10), 3635; https://doi.org/10.3390/s22103635 - 10 May 2022

Cited by 6 | Viewed by 3597

Abstract

Over the past decade, there has been exponential growth in the per capita rate of medical patients around the world, and this is significantly straining the resources of healthcare institutes. Therefore, the reliance on smart commercial off-the-shelf (COTS) implantable wireless medical devices (IWMDs) is increasing among healthcare institutions to provide routine medical services, such as monitoring patients’ physiological signals and the remote delivery of therapeutic drugs. These smart COTS IWMDs reduce the necessity of recurring visits of patients to healthcare institutions and also mitigate physical contact, which can minimize the possibility of any potential spread of contagious diseases. Furthermore, the devices provide patients with the benefit of recuperating in familiar surroundings. As such, low-cost, ubiquitous COTS IWMDs have engendered the proliferation of telemedicine in healthcare to provide routine medical services. In this paper, a review work on COTS IWMDs is presented at a macro level to discuss the history of IWMDs, different networked COTS IWMDs, health and safety regulations of COTS IWMDs and the importance of organized procurement. Furthermore, we discuss the basic building blocks of IWMDs and how COTS components can contribute to build these blocks over widely researched custom-built application-specific integrated circuits. Full article

(This article belongs to the Special Issue Selected Papers from the 8th International Electronic Conference on Sensors and Applications)

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