A fully textile-based, tunable, force and strain sensing resistor for e-textile applications

This work presents a novel approach towards integrating electronic components with textiles, by successfully creating a fully textile-based element that is capable of detecting applied forces by variation in its resistance value. The fabrication of the device consists of a specialized siliconized conductive fabric, which is placed above and below a layer of switch fabric, which acts as a force sensor. In this paper, the effects of three different geometries are observed, as well as the washability of the device, along with tension testing. Μoreover, the device behavior is simulated as well as applied in a real-life scenario. The proposed element demonstrates a good dynamic range, high repeatability and stability, and minimal impact of washing, creating a great candidate for integration in e-textiles.

A novel method for in-situ extracting bio-impedance model parameters optimized for embedded hardware

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.

Wearable humidity sensor embroidered on a commercial face mask and its electrical properties

Owing to the rapid development in the field of e-textile-based flexible and portable sensors, the present work demonstrates a fully textile-based stretchable face mask humidity sensor which was created using digital embroidery technique. The design of the sensor was comprised of interdigitated structured electrodes made up of polymer core-based conductive silver-coated threads and hygroscopic threads embedded between them. The fabricated sensor performed well towards moisture detection in accordance with the principle where resistance of the face mask sensor decreased with the increase in the relative humidity along with the changing operational frequency in the range from 1 Hz to 200 kHz. The electrical response (resistance, impedance, capacitance and phase angle) of the novel thread-based sensor towards change in relative humidity was recorded and showed in the present work. The embroidery of polymer-based threads onto the face mask towards humidity sensing offers a novel wearable platform for more extended biomedical applications for detection of various breath biomarkers and thus early diagnosis of diseases.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10853-022-08135-2.

Portable Heating and Temperature-Monitoring System with a Textile Heater Embroidered on the Facemask

Personal heating systems are getting increasing interest because of the need to reduce the negative impact of cold weather on the health of people and animals. Heating the air before inhalation is of great importance as it can reduce the probability of various diseases. In this paper, we present a textile-based heater composed of commercial conductive threads, embroidered on an ordinary protective facemask. We also present the design and implementation details of the temperature monitoring and controlling circuit. Air temperature inside the facemask was monitored by a thermocouple placed in close proximity to the nose (nostrils). Preliminary testing revealed that the difference among temperatures in repeated heating cycles is in the range of ±1.5 °C. The response time for temperature increase from 29.9 to 40.5 °C was about 4 min, while the recovery time from 40.5 to 31.3 °C was about 4.3 min. Safety for human use and wireless data transmission to an application installed on a mobile phone are also demonstrated.

Gold Leaf-Based Microfluidic Platform for Detection of Essential Oils Using Impedance Spectroscopy

Drug delivery systems are engineered platforms for the controlled release of various therapeutic agents. This paper presents a conductive gold leaf-based microfluidic platform fabricated using xurography technique for its potential implication in controlled drug delivery operations. To demonstrate this, peppermint and eucalyptus essential oils (EOs) were selected as target fluids, which are best known for their medicinal properties in the field of dentistry. The work takes advantage of the high conductivity of the gold leaf, and thus, the response characteristics of the microfluidic chip are studied using electrochemical impedance spectroscopy (EIS) upon injecting EOs into its micro-channels. The effect of the exposure time of the chip to different concentrations (1% and 5%) of EOs was analyzed, and change in electrical resistance was measured at different time intervals of 0 h (the time of injection), 22 h, and 46 h. It was observed that our fabricated device demonstrated higher values of electrical resistance when exposed to EOs for longer times. Moreover, eucalyptus oil had stronger degradable effects on the chip, which resulted in higher electrical resistance than that of peppermint. 1% and 5% of Eucalyptus oil showed an electrical resistance of 1.79 kΩ and 1.45 kΩ at 10 kHz, while 1% and 5% of peppermint oil showed 1.26 kΩ and 1.07 kΩ of electrical resistance at 10 kHz respectively. The findings obtained in this paper are beneficial for designing suitable microfluidic devices to expand their applications for various biomedical purposes.

Polymer-Thread-Based Fully Textile Capacitive Sensor Embroidered on a Protective Face Mask for Humidity Detection

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.

Implants with Sensing Capabilities

Because of the aging human population and increased numbers of surgical procedures being performed, there is a growing number of biomedical devices being implanted each year. Although the benefits of implants are significant, there are risks to having foreign materials in the body that may lead to complications that may remain undetectable until a time at which the damage done becomes irreversible. To address this challenge, advances in implantable sensors may enable early detection of even minor changes in the implants or the surrounding tissues and provide early cues for intervention. Therefore, integrating sensors with implants will enable real-time monitoring and lead to improvements in implant function. Sensor integration has been mostly applied to cardiovascular, neural, and orthopedic implants, and advances in combined implant-sensor devices have been significant, yet there are needs still to be addressed. Sensor-integrating implants are still in their infancy; however, some have already made it to the clinic. With an interdisciplinary approach, these sensor-integrating devices will become more efficient, providing clear paths to clinical translation in the future.

A randomized, double-blind, placebo-controlled study evaluating the efficacy of propolis and N-acetylcysteine in exacerbations of chronic obstructive pulmonary disease

OBJECTIVE

Acute exacerbations of chronic obstructive pulmonary disease (AECOPDs) accelerate the progressive impairment of lung function and general health. Together with maintenance therapy for chronic obstructive pulmonary disease (COPD), N-acetylcysteine (NAC) and natural propolis have demonstrated pharmacological properties that address crucial pathophysiological processes underlying COPD and may prevent AECOPDs. This study aims at responding to dose-dependent efficacy and safety concerns regarding a propolis-NAC combination for the reduction of COPD exacerbation rates.

PATIENTS AND METHODS

This was a single-center, randomized, double-blind, phase IV trial with three treatment arms: Placebo and two active substance groups, one (AS-600) received 600 mg of NAC + 80 mg of propolis while the other (AS-1,200) received 1,200 mg of NAC + 160 mg of propolis. Following an AECOPD, frequent-exacerbation phenotype patients (n=46) were assigned a once-daily three-month therapy with the study drug and one year follow-up. The primary endpoint was the COPD exacerbation incidence rate during the follow-up period as a measure of dose-dependent efficacy of NAC-propolis combination compared to placebo.

RESULTS

There was a statistically significant difference in the AECOPD incidence rate: 52.6% in patients that received placebo, 15.4% that received AS-600 and only 7.1% that received AS-1,200 (Fisher's exact test, p = 0.013). Compared to placebo, AECOPD frequency was significantly lower only in AS-1,200 (p=0.009). Compared to placebo, the relative risk for exacerbation was 0.29 in AS-600 and 0.13 in AS-1,200. No adverse events related to the treatment were reported.

CONCLUSIONS

Oral combination of natural propolis with NAC confirmed formulation efficiency with a favorable safety profile. Our results need to be confirmed by larger clinical trials.

Chemical vs. Physical Methods to Improve Dermal Drug Delivery: A Case Study with Nanoemulsions and Iontophoresis

So far, various approaches have been proposed to improve dermal drug delivery. The use of chemical penetration enhancers has a long history of application, while methods based on the electrical current (such as iontophoresis) stand out as promising “active” techniques. Aiming to evaluate the contribution of different approaches to dermal delivery, in this work curcumin-loaded nanoemulsions with and without monoterpenes (eucalyptol or pinene) as chemical penetration enhancers, and a custom-made adhesive dermal delivery system based on iontophoresis were designed and assessed. In an in vivo study applying skin bioengineering techniques, their safety profile was proven. Three examined iontophoresis protocols, with total skin exposure time of 15 min (continuous flow for 15 min (15-0); 3 min of continuous flow and 2 min pause (3-2; 5 cycles) and 5 min of continuous flow and 1 min pause (5-1; 3 cycles) were equally efficient in terms of the total amount of curcumin that penetrated through the superficial skin layers (in vivo tape stripping) (Q3-2 = 7.04 ± 3.21 μg/cm2; Q5-1 = 6.66 ± 2.11 μg/cm2; Q15-0 = 6.96 ± 3.21 μg/cm2), significantly more efficient compared to the referent nanoemulsion and monoterpene-containing nanoemulsions. Further improvement of an efficient mobile adhesive system for iontophoresis would be a practical contribution in the field of dermal drug application.

Portable Respiration Monitoring System with an Embroidered Capacitive Facemask Sensor

Respiration monitoring is a very important indicator of health status. It can be used as a marker in the recognition of a variety of diseases, such as sleep apnea, asthma or cardiac arrest. The purpose of the present study is to overcome limitations of the current state of the art in the field of respiration monitoring systems. Our goal was the development of a lightweight handheld device with portable operation and low power consumption. The proposed approach includes a textile capacitive sensor with interdigitated electrodes embroidered into the facemask, integrated with readout electronics. Readout electronics is based on the direct interface of the capacitive sensor and a microcontroller through just one analog and one digital pin. The microcontroller board and sensor are powered by a smartphone or PC through a USB cable. The developed mobile application for the Android™ operating system offers reliable data acquisition and acts as a bridge for data transfer to the remote server. The embroidered sensor was initially tested in a humidity-controlled chamber connected to a commercial impedance analyzer. Finally, in situ testing with 10 volunteering subjects confirmed stable operation with reliable respiration monitoring.

Silver Conductive Threads-Based Embroidered Electrodes on Textiles as Moisture Sensors for Fluid Detection in Biomedical Applications

Wearable sensors have become part of our daily life for health monitoring. The detection of moisture content is critical for many applications. In the present research, textile-based embroidered sensors were developed that can be integrated with a bandage for wound management purposes. The sensor comprised an interdigitated electrode embroidered on a cotton substrate with silver-tech 150 and HC 12 threads, respectively, that have silver coated continuous filaments and 100% polyamide with silver-plated yarn. The said sensor is a capacitive sensor with some leakage. The change in the dielectric constant of the substrate as a result of moisture affects the value of capacitance and, thus, the admittance of the sensor. The moisture sensor's operation is verified by measuring its admittance at 1 MHz and the change in moisture level (1-50) µL. It is observed that the sensitivity of both sensors is comparable. The identically fabricated sensors show similar response and sensitivity while wash test shows the stability of sensor after washing. The developed sensor is also able to detect the moisture caused by both artificial sweat and blood serum, which will be of value in developing new sensors tomorrow for smart wound-dressing applications.

Biomonitoring for wide area surveying in landmine detection using honeybees and optical sensing

Humanitarian demining is a worldwide effort and the range of climates and environments prevent any one detection method being suitable for all sites, so more tools are required for safe and efficient explosives sensing. Landmines emit a chemical flux over time, and honeybees can collect the trace residues of explosives (as particles or as vapour) on their body hairs. This capability was exploited using a passive method allowing the honeybees to freely forage in a mined area, where trace explosives present in the environment stuck to the honeybee body, which were subsequently transferred onto an adsorbent material for analysis by a fluorescent polymer sensor. Potential false positive sources were investigated, namely common bee pheromones, the anti-varroa pesticide Amitraz, and the environment around a clean apiary, and no significant response was found to any from the sensor. The mined site gave a substantial response in the optical sensor films, with quenching efficiencies of up to 38%. A model was adapted to estimate the mass of explosives returned to the colony, which may be useful for estimating the number of mines in a given area.

Performances and Biosensing Mechanisms of Interdigitated Capacitive Sensors Based on the Hetero-mixture of SnO2 and In2O3

This study aims to discuss the synthesis and fabrication of SnO₂-In₂O₃-based thick-films and their biosensing applications. The structural characterization of SnO₂-In₂O₃ nanocomposites was performed using X-ray diffraction, Raman spectroscopy and transmission electron microscopy. Furthermore, the screen-printing technology was used in the fabrication of conductive electrodes to form an interdigitated capacitive structure, and the sensor layer based on the mixture of SnO₂ and In₂O₃. Moreover, the sensing performance of the developed structure was tested using Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) bacteria. In addition, the validation of sensing characteristics was performed by electrochemical impedance spectroscopic and self-resonant frequency analysis. Finally, the sensing properties were analyzed for two consecutive days, and changes in both P. aeruginosa and S. aureus pathogens growing media were also studied.

Preliminary assay on the antioxidative activity of Laurus nobilis extracts

Antioxidative activity of Laurus nobilis leaves, bark and fruit methanolic extracts (crude and defatted) were studied on the level of lipid peroxidation in liposomes, induced by Fe(2+)/ascorbate system and measured spectrophotometrically by the TBA-test. The most significant inhibition of lipid peroxidation was obtained with methanolic extracts of laurel bark (70.6% of inhibition was obtained with 1.0 mg of crude extract).

Survey of natural and anthropogenic radioactivity in environmental samples from Yugoslavia

The radioactivity of 238U, 226Ra, 232Th, 40K and 137Cs in sediments, soil, turf and honey from Serbia and Kosovo (Yugoslavia) was measured using gamma and alpha spectrometry in order to estimate the radiation hazard from natural and man-made sources, as well as to compile a database for radioactivity levels in those regions. One sample, collected in the vicinity of a "depleted uranium" (DU) shell of the recent Balkan war, revealed a high 238U activity and a non-natural 235U/238U activity ratio, confirming therefore its anthropogenic origin. However, some other soil samples coming from characteristic DU craters did not show any characteristic level of radioactivity. The other sediment and turf samples taken all around the country show low radioactivity levels for all the isotopes here considered. With the aim of obtaining some indication about radioactivity migration in the food chain, several honey samples have been examined too. All samples show very low radioactivity content, often indistinguishable from natural background.

Early diagnosis and treatment of ectopic pregnancy

During the period from 1995 to 1999, 64 patients were treated for ectopic pregnancy. All patients admitted to the department passed the same procedure including (complete preoperative laboratory findings, Beta HCG, serum progesterone and transvaginal colour Doppler). In patients who had ultrasound finding typical for ectopic pregnancy in combination with positive Beta HCG, conservative treatment was primarily done. In the rest of the patients, Beta HCG was tested every second day and in combination with the clinical and vaginosonographical findings the patients underwent diagnostic or operative laparoscopy. Out of 64 patients 36 had visible ectopic pregnancy when admitted to the clinical department. Three patients had no visible ectopic pregnancy neither at the time of their admission to the department nor at the time of laparoscopy. One of them had cervical pregnancy and the other two had pregnancies in the uterine part of the tube. The patient with cervical pregnancy was treated with metrotrexat (MTX) 12 mg daily in 5 doses. One patient with cornual pregnancy was treated with high doses of oxytocin infusion in combination with MEB intravenously 3 x 1 amp. The other patient with cornual pregnancy underwent laparoscopy with cornual resection and salpingectomy. Four of other tubar pregnancies were treated with metrotrexat 12 mg/day for 5 days. Other ectopic pregnancies were treated as follows: 36 laparoscopic salpingectomies, 10 laparoscopic salpingotomies with ovum expression, 9 adnexectomies by laparotomy, and 2 laparoscopic adnexectomies.

Attitudes, behaviour and knowledge on sexuality among female adolescents in Zagreb, Croatia

The aim of this study was to estimate the level of knowledge about sexuality, attitudes and sexual behaviour of female adolescents. The study included 194 female students, 117 from Medical High School (MHS) and 77 from General High School (GHS) in Zagreb. Data was collected using an anonymous self-administered questionnaire. In addition to items on personal data (age, parental education etc.), the participants were asked to define terms about sexuality (e.g. menstruation, puberty) the definitions of which are found in biology textbooks for the fifth and eighth grade of primary school. The aim of the third part of the survey was to collect information about attitudes and behaviour of female adolescents. The results showed a low level of knowledge in students of both schools. General High School students showed a higher level of knowledge than their Medical High School peers. One fifth of General High School students and 1/3 of Medical High School students were unable to define the term "menstruation". The majority of adolescents talk about sexuality with their friends, 92.1% of General High School and 81.2% of Medical High School students. Almost 50% of students of both schools would like to talk about sexuality with their school doctor. 6.9% of Medical High School students had at least one sexual intercourse while none of the General High School students had been sexually active at the time of the survey. As the majority of students were not sexually active and results showed a rather low level of knowledge, this seems to be the ideal period for the implementation of educational programs aimed at increasing the level of knowledge, and thus preventing unwanted consequences (STD, pregnancy, abortion, infertility).

Removal of detergent and solvent from solvent-detergent-treated immunoglobulins

The solvent-detergent (S/D) method was applied for inactivation of lipid-enveloped viruses during the production of immunoglobulins. Amberlite XAD-7 resin was used for removal of solvent (tri-n-butyl phosphate, TnBP) and detergent (Triton X-100) after the performed S/D inactivation procedure. The S/D reagents from the immunoglobulin preparation were adsorbed on Amberlite XAD-7, while immunoglobulins passed through the column and retained their biological activity. Using the method developed here, the final immunoglobulin preparation contains less than 1 ppm of Triton X-100 and less than 2 ppm TnBP.

Ion-exchange chromatography separation of the detergent and the solvent from immunoglobulins after solvent-detergent treatment

For inactivation of lipid-enveloped viruses during the immunoglobulin production, the solvent-detergent (S/D) method was applied. Tri-n-butyl phosphate (solvent) and Triton X-100 (detergent) were removed from S/D treated immunoglobulins by ion-exchange chromatography on Q-Sepharose Fast Flow (FF). During the chromatographic procedure immunoglobulins remained bound on a Q-Sepharose FF, whereas solvent and detergent were eluted by washing with starting buffer. Elution of immunoglobulins was achieved by increasing the ionic strength of the starting buffer. The final immunoglobulin preparation contained less than 10 microg/ml of Triton X-100 and less than 2 microg/ml tri-n-butyl phosphate. It was confirmed that the S/D procedure did not cause a significant change in polymers and specific antibodies content. Immunoglobulin classes were also not affected by the same procedure.

[Epizootiologic situation of rabies in 1997. Urbanization of sylvatic rabies in Yugoslavia]

The Federal Republic of Yugoslavia is situated on the border of a great sylvatic rabies epizootics occurring in central and eastern Europe. That is the reason why a relatively small number of rabid animals have been registered. In 1997, 124 rabid animals, mainly red foxes, were identified. In recent years red fox rabies epizootics in Yugoslavia has annually spread 15-20 km to the south. Rabies in domestic animals, especially dogs, was characterized with furious clinical forms and dog-to-dog transmission typical of urban rabies. Sylvatic rabies has been almost completely eradicated in some countries of western Europe in the last years, mostly due to the method of oral vaccination of foxes-the main vector of rabies.

Circulating inhibitor of interleukin 1 activity in patients with chronic renal diseases

The effects of sera derived from patients suffering from chronic renal diseases (endemic Balkan nephropathy, glomerulonephritis and pyelonephritis) on T cell proliferative response was studied. It was found that these sera contained factors which affect interleukin 1 (IL-1) dependent events in T cell proliferative response. The factors prevent costimulatory effects of IL-1 on T cells but do not bind to IL-1, nor do they affect interleukin 2 (IL-2) dependent T cell proliferation. These findings indicate that immuno-suppression observed in some kidney disorders may be partially due to serum immunoinhibitory factors affecting IL-1 activity.

[Morphologic characteristics of the liver allograft in experimental warm ischemia]

Thirty-minute normothermic liver ischemia causes swelling of the hepatocytes and sinusoid wall cells, their individual necrosis and discharge of the glycogen supply in the hepatocytes. The swelling of the hepatocytes and of the sinusoid wall cells causes a significant reduction of the liver lobe sinusoid volume which decreases from 27.6% to 5.4%, representing, actually, one fifth of the normal value. Such finding was recorded as a critical vascular liver volume, because any further decrease of the sinusoid volume would inevitably lead toward manifest and persisting portal hypertension which evidently interferes with Bernoulli trial of the hepatitic perfusion. The obtained data determine morphofunctional relevancy of the liver allograft for transplantation and are useful for all other surgical interventions requiring partial resection of this organ or time limited regional and total ischemia.

[The significance of synergism between cervical infections and prostaglandins in inducing preinduction priming in the 3rd trimester of pregnancy]

The length of labour and foetal trauma could be significantly reduced by reduction of cervical resistance in the cause of labour. It is well known that the most effective way of priming is by prostaglandins. Microorganisms of cervico-vaginal flora, with or without inflammatory component, can produce factors which can create predisposition for preterm delivery. Namely, increased levels of prostaglandins E2 and F2 alpha could be noticed in amniotic fluids, compared with these levels in pregnant women without signs of infection. The study included 60 parturients with low Bishop score (less then 5), with average gestational age of 40.5 weeks. Group A: Prepidil gel with 0.5 mg of prostaglandin E2 was applied to cause priming. Group B: Half of doses of Prepidil gel (0.25 mg) was applied to the 30 patients with clinical signs and with positive laboratory findings of cervical infection. After 12 hours all patients were induced with oxytocin. All obstetrically important parameters were closely followed in the course of priming and induction. Presence of cervical infection could be beneficial, because priming can be produced with half of doses of prostaglandin, which means medical (reduction of side-effects and dangers of hyperstimulation) and significant economical benefits regarding the high price of prostaglandins.

[Mucopolysaccharidosis type I, Hurler's syndrome]

A 5-year-old girl with a very rare autosomal recessive disease, Hurler's syndrome, is described. This is a progressive disease and the main symptoms, typical for metabolic disorders of mucopolysaccharides were present. Only intransprarent cornea was not manifest, as it usually appears in advanced age. Dental examination confirmed the following symptoms: hypertrophic alveolar process; spaced, carious teeth; long tongue; enamel hypoplasia; hypocalcification; open teeth occlusion, etc. The prognosis is characterized by aggravation of symptoms till death in the second decade of life. The therapy is symptomatic.

[Morpho-etiologic problems of pseudomembranous lesions of the colon]

Pseudomembranous colitis (PMC) is an infectious colon disease caused by Cl. difficile toxin. Each change of the intraluminal microbiological balance as well as damages of the hemato-enteral barrier may cause changes in the enteral flora and selective proliferation of anaerobic bacterial strains. PMC has been most frequently described after enteral application of antibiotics, even of those with the broadest use. In nonocclusive mesenterial ischemia changes similar to postantibiotic PMC may occur but pseudomembranous changes are confluent and associated with haemorrhagia and microthromboses. Some systemic and chronic inflammatory diseases of the colon may be a basis for development of anaerobic Cl. difficile which one should have in mind at establishing endoscopic and bioptic diagnosis.