Mitar Simić - Academia.edu (original) (raw)

Papers by Mitar Simić

Scientific Reports

A novel method for embedded hardware-based parameter estimation of the Cole model of bioimpedance... more A novel method for embedded hardware-based parameter estimation of the Cole model of bioimpedance is developed and presented. The model parameters R∞, R1 and C are estimated using the derived set of equations based on measured values of real (R) and imaginary part (X) of bioimpedance, as well as the numerical approximation of the first derivative of quotient R/X with respect to angular frequency. The optimal value for parameter α is estimated using a brute force method. The estimation accuracy of the proposed method is very similar with the relevant work from the existing literature. Moreover, performance evaluation was performed using the MATLAB software installed on a laptop, as well as on the three embedded-hardware platforms (Arduino Mega2560, Raspberry Pi Pico and XIAO SAMD21). Obtained results showed that the used platforms can perform reliable bioimpedance processing with the same accuracy, while Raspberry Pi Pico is the fastest solution with the smallest energy consumption.

Textile Research Journal

As textile electronics has undergone a boom in the past few decades, especially the sensing aspec... more As textile electronics has undergone a boom in the past few decades, especially the sensing aspect, methods of modular connectivity of these components with classical electrical components and printed circuit boards must be broadened. This study focuses on the aforementioned problem, as well as testing the electrical properties of conductive textile lines through a series of experiments. Fabrication of the conductive structure was done in two parts: embroidery of the conductive threads onto cloths, as well as designing and three-dimensional printing of connectors that will be used for bridging and making a stable connection with pin-based systems. A valid connection between the textile endings and pins has not yet been tested, and is the main focus of this paper, aside from testing outside influences on the designed textile structure. Afterwards, the developed prototype was tested through a realistic scenario that consisted of body temperature validations and the application of arti...

Applied Sciences

Essential oils (EOs) have a long tradition of use in the medical and cosmetic fields based on the... more Essential oils (EOs) have a long tradition of use in the medical and cosmetic fields based on their versatile properties, including fungicidal, antiparasitic, and bactericidal effects. Nowadays, with the development of industry and electronics, EOs are increasingly being used in the agricultural and food industries; health industries, including pharmacy and dental medicine; and as cosmetic enhancements. The purpose of this study is to develop a compact and portable platform for the detection of EO type and the concentration levels using knitted silver threads. The method is based on measuring the variation in values of the electrical parameters of the silver threads using electrochemical impedance spectroscopy (EIS). The impedance of the solutions applied on the testing platform was measured in the frequency range from 1 Hz to 200 kHz. The platform was tested using three types of essential oils: tea tree; clary sage; and cinnamon bark oil. Increasing the concentration of essential o...

ACS Omega

The COVID-19 pandemic has created a situation where wearing personal protective masks is a must f... more The COVID-19 pandemic has created a situation where wearing personal protective masks is a must for every human being and introduced them as a part of everyday life. This work demonstrates a new functionality embedded in single-use face masks through an embroidered humidity sensor. The design of the face mask humidity sensor is comprised of interdigitated electrodes made of polyamide-based conductive threads and common polyester threads which act as a dielectric sensing layer embroidered between them. Therefore, the embroidered sensor acts as a capacitor, the performance of which was studied in increasing humidity conditions in the frequency range from 1 Hz to 100 kHz. The moisture adsorbed by sensitive hygroscopic polyester threads altered their dielectric and permittivity properties which were detected by the change in capacitance values of the face mask sensors at different relative humidity (RH) levels. The calculated limit of detection (LOD) values for the two proposed sensors at different frequencies (1, 10, and 100 kHz) were found in the range from 11.46% RH−27.41% RH and 29.79% RH−38.65% RH. The tested sensors showed good repeatability and stability under different humidity conditions over a period of 80 min. By employing direct embroidery of silver-coated polyamide conductive threads and moisture-sensitive polyester threads onto the face mask, the present work exploits the application of polymer-based textile materials in developing novel stretchable sensing devices toward e-textile applications.

Polymers

In recent years, after the ongoing success in the creation of portable electronic devices, an inc... more In recent years, after the ongoing success in the creation of portable electronic devices, an increasing effort has been put in creating wearable devices capable of sensing multiple parameters while being imperceptible to the user. A field that has recently gained attention due to this is that of textile electronics. For this purpose, one of the most commonly used materials is conductive threads, capable of sustaining an electrical connection, while at the same time being part of a garment. As research on the performance and stability of such threads is scarce, the aim of this work is to study the effects of tension on readily available conductive threads and to verify their suitability and reliability for e-textile applications. After testing seven commercially available threads, this study demonstrates that the nominal parameters provided by the manufacturers are not in line with experimentation, and that both embroidery and washing have an impact on their performance.

International Journal of Precision Engineering and Manufacturing-Green Technology

Following the circular economy concept, all areas of science, including electronics, require indi... more Following the circular economy concept, all areas of science, including electronics, require individual approach. The green electronics approach implies processing natural based materials for development of electronic components even for single use, so that waste does not exist. This paper describes the production of thermistors from 3 different types of edible materials, their testing in laboratory conditions, as well as the application for measuring the temperature in the human oral cavity. To make the thermistor, three types of natural materials were used (carrageenan, polyvinyl alcohol and apple pomace-based). After fabrication, materials were poured into molds. Aluminium foil contacts were placed so that the electrical characterization of the materials could be performed. Several parameters were measured: resistance (R), impedance (Z) and the phase angle (θ) as a function of frequency. In order to determine whether the thermistors have a positive or negative temperature coeffic...

2023 22nd International Symposium INFOTEH-JAHORINA (INFOTEH)

Deep learning models for image classification are typically trained under the "closed-world" assu... more Deep learning models for image classification are typically trained under the "closed-world" assumption with a predefined set of image classes. However, when the models are deployed they may be faced with input images not belonging to the classes encountered during training. This type of scenario is common in remote sensing image classification where images come from different geographic areas, sensors, and imaging conditions. In this paper we deal with the problem of detecting remote sensing images coming from a different distribution compared to the training dataout of distribution images. We propose a benchmark for out of distribution detection in remote sensing scene classification and evaluate detectors based on maximum softmax probability and nearest neighbors. The experimental results show convincing advantages of the method based on nearest neighbors.

IEEE Transactions on Instrumentation and Measurement

Jedan od doprinosa ove disertacije je realizacija modela prenosivog mernog sistema za karakteriza... more Jedan od doprinosa ove disertacije je realizacija modela prenosivog mernog sistema za karakterizaciju senzora uz mogućnost daljinskog pristupa rezultatima merenja. U LTCC tehnologiji je fabrikovan senzor za merenje pH vrednosti, na bazi TiO2 filma na alumina substratu, koji je karakterisan razvijenim mernim sistemom. Izvršena je i obrada podataka dobijenih prilikom karakterizacije senzora formiranjem polinomske statičke karakteristike i modelovanjem senzora ekvivalentnom električnom mrežom. Predložen je novi neiterativni metod estimacije vrednosti parametara modela koji, u poređenju sa metodom najmanjih kvadrata, omogućava jednostavniju estimaciju uz kraće vreme izvršavanja.One of the contributions of this research is a model of the portable electronic measurement system for sensors characterization with remote access to the measurement results. In LTCC technology a TiO2-based pH sensor is fabricated on the alumina substrate and it was characterized with developed measurement system...

2022 21st International Symposium INFOTEH-JAHORINA (INFOTEH)

Beehive monitoring systems are very important for understanding behavior of bees and to have a be... more Beehive monitoring systems are very important for understanding behavior of bees and to have a better overview of environmental parameters impact on their activities. Such information is very useful for agriculture, but in saving bees as well. Although there are various systems for monitoring beehives, there is still a growing need for low-cost monitoring solutions. In this paper we proposed an integrated system for video-based honey bee counting and a multi-sensors platform for environmental parameters monitoring. The honey bees counting system aims to evaluate foraging activity of bees through the number of honey bees exiting and entering the beehive, while the multi-sensors platform is used for remote monitoring of environmental parameters near the beehive. The proposed electronic system for remote monitoring of environmental parameters in a bee yard has specific features such as battery-power supply, portability, and a unit for transmitting data to the remote server. On a relatively small data set, that includes measured and acquisitioned environmental parameters as well as counted honey bees, we have shown how effort of honey bees is coupled to the coincident environmental parameters near the hive.

2016 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), 2016

Modern research directions in smart environment include analysis of factors that influence overal... more Modern research directions in smart environment include analysis of factors that influence overall human Quality of Life (QoL). Context influence factors (CIF) are unavoidable within smart environment research. In this paper, we address indoor air quality (IAQ) as one of the main CIF. The major contaminants of indoor air are CO2 and volatile organic compounds (VOCs). There are still no satisfactory methods for air pollutants monitoring and removal. The ability of plants to detoxify these compounds makes biological systems the promising technologies for this purpose. Although precise mechanisms how plants remove VOC are unknown and current knowledge is based on experiments conducted under controlled conditions, it does not prevent us not to use biological air purifiers. Our measurements under uncontrolled conditions in environments where people live, showed that houseplants' ability to reduce VOC differs from one to another environment. Instead of attempt to design the unique botanical system for air purification, we proposed internet of things (IoT) based methodology for continuous monitoring and objective assessment of IAQ aiming to improve the designing and adaptation of botanical purifiers to specific environment, user's health, living habits and requirements.

2021 International Balkan Conference on Communications and Networking (BalkanCom), 2021

In this paper we present results of the simulation analysis of the impact of transmission paramet... more In this paper we present results of the simulation analysis of the impact of transmission parameters and distance between LoRa node and gateway on communication performance (packet loss rate and energy consumed by nodes). FLoRa simulation framework based on Omnet++ was used to vary spreading factor, bandwidth, coding rate and transmission power. For given distance of 100 m, Lora gateway successfully received the packets in 80 configurations. In particular case, when the distance between node and gateway was doubled, just 8 configurations were able to deliver the packets. Finally, we used 5 values of path loss variance in range from 0 to 7.08 dB with a distance of 400 m, and the success rate of data transmission from node to the gateway decreased to 48.83%.

IEEE Sensors Journal, 2021

In this paper we present a processing-efficient method for parameter estimation of a Randles circ... more In this paper we present a processing-efficient method for parameter estimation of a Randles circuit. As our approach is not iterative, it does not require for an initial guess of model parameters to be provided. The low-complexity of the provided set of closed-form expressions enables the implementation on microcontroller-based platforms. The presented approach is verified with simulations (using both noiseless data and data with noise) and with experimentally obtained data (Randles circuit made from discrete components; impedance of microfluidic platform for isomalt detection; impedance of Panasonic 18650PF Li-ion Battery). Additionally, it was implemented on a microcontroller board based on ATmega2560 microcontroller with available 256 kB of flash memory, 8 kB of SRAM and clock speed of 16 MHz. Reliable and accurate estimations of such implementations confirmed the suitability of this work for low-cost embedded hardware.

Advances in Electrical and Computer Engineering, 2016

Parameter estimation of Fricke-Morse model of biological tissue is widely used in bioimpedance da... more Parameter estimation of Fricke-Morse model of biological tissue is widely used in bioimpedance data processing and analysis. Complex nonlinear least squares (CNLS) data fitting is ofte ...