Bio: Silvan Pretl is an academic researcher from University of West Bohemia. The author has contributed to research in topics: PEDOT:PSS & Conductive polymer. The author has an hindex of 5, co-authored 23 publications receiving 97 citations.
TL;DR: In this paper, a chemoresistive ammonia sensor with sensitive polyaniline layer has been fabricated by gravure printing on flexible poly(ethylene terephthalate) substrate.
Abstract: A chemoresistive ammonia sensor with sensitive polyaniline layer has been fabricated by gravure printing on flexible poly(ethylene terephthalate) substrate. Novel colloids of polyaniline hydrochloride, which were synthetized in xylene or chloroform in the presence of surfactant, were used as a printing formulation. The sensor characteristics of the colloid-based sensitive layers were compared with in-situ polymerized layers of polyaniline. The colloid-based sensors showed a good response to ammonia concentrations in the range from hundreds of ppb to tens of ppm. This provides an opportunity to use these sensors for both monitoring of maximum exposure limits for humans in workplaces as well as environmental air-pollution. Therefore, these fully printed, metal-free, low cost and flexible ammonia sensors based on organic materials can be used in detection systems for monitoring of hazardous gases.
TL;DR: In this paper, a self-standing humidity sensor was fabricated from sugarcane side streams using cellulose nanofibril (CNF) and polyethylene glycol (PEG) to improve the ductility of CNF films.
Abstract: Cellulose nanofibril (CNF) films were prepared from side streams generated by the sugarcane industry, that is, bagasse. Two fractionation processes were utilized for comparison purposes: (1) soda and (2) hot water and soda pretreatments. 2,2,6,6‐Tetramethylpiperidinyl‐1‐oxyl‐mediated oxidation was applied to facilitate the nanofibrillation of the bagasse fibers. Poly(ethylene glycol) (PEG) was chosen as plasticizer to improve the ductility of CNF films. The neat CNF and biocomposite films (CNF and 40% PEG) were used for fabrication of self‐standing humidity sensors. CNF‐based humidity sensors exhibited high change of impedance, within four orders of magnitude, in response to relative humidity (RH) from 20 to 90%. The use of plasticizer had an impact on sensor kinetics. While the biocomposite film sensors showed slightly longer response time, the recovery time of these plasticized sensors was two times shorter in comparison to sensors without PEG. This study demonstrated that agroindustrial side streams can form the basis for high‐end applications such as humidity sensors, with potential for, for example, packaging and wound dressing applications.
••01 May 2017
TL;DR: In this article, a flexible RFID smart tag for temperature monitoring is presented. The system is based on a single chip solution working at 13.56 MHz according to ISO 15693.
Abstract: This paper describes development of flexible RFID smart tag for temperature monitoring. The system is based on a single chip solution working at 13.56 MHz according to ISO 15693. This standard is supported by Android API and Android smartphones with NFC periphery. The developed prototype of the smart tag was realized by hybrid technology combining printed RFID antenna with the SMD chip and flexible battery assembled using conductive adhesive. The size of the smart tag complies with the ISO/IEC 7810 Card size ID-1 (85.60 mm × 53.98 mm). Measurement settings and data readout is realized by software developed for NFC-equipped mobile devices with Android operating system. The whole system represents a cost effective solution to the cold chain temperature monitoring of sensitive commodities within the logistic chain.
06 Dec 2020
TL;DR: It is obvious that fully printed sensor elements based on cheap and environmentally friendly carbon layers printed on the wood substrate can compete with conventionally made sensors based on copper.
Abstract: Digitization of industrial processes using new technologies (IoT—Internet of Things, IoE—Internet of Everything), including the agriculture industry, are globally gaining growing interest. The precise management of production inputs is essential for many agricultural companies because limited or expensive sources of water and nutrients could make sustainable production difficult. For these reasons, precise data from fields, plants, and greenhouses have become more important for decision making and for the proper dosage of water and nutrients. On the market are a variety of sensors for monitoring environmental parameters within a precise agricultural area. However, the high price, data storage/transfer functionality are limiting so cost-effective products capable to transfer data directly to farmers via wireless IoT networks are required. Within a given scope, low-price sensor elements with an appropriate level of sensor response are required. In the presented paper, we have developed fully printed sensor elements and a dedicated measuring/communicating unit for IoT monitoring of soil moisture. Various fabrication printing techniques and a variety of materials were used. From the performed study, it is obvious that fully printed sensor elements based on cheap and environmentally friendly carbon layers printed on the wood substrate can compete with conventionally made sensors based on copper.
••01 May 2016
TL;DR: In this article, the authors present a research focused on the testing of flexible and printed components' mechanical properties, focusing on the development of bend test apparatus, as well as, on the specification and optimization of testing procedures.
Abstract: This paper presents a research focused on the testing of flexible and printed components' mechanical properties. The flexibility and the bending endurance are the crucial properties for the production of smart labels and tags for smart packages. For these reasons, the presented research was concentrated on the development of bend test apparatus, as well as, on the specification and optimization of testing procedures. These procedures were verified on specially designed conductive test patterns manufactured by the use of three different technologies — standard flexible PCB manufacturing, screen printing of Ag pastes and Aerosol Jet® printing of Ag ink. Electrical parameters of test patterns were measured online and offline during the testing. The influences of test samples' electrical resistance on the number of bend cycles for different bending radiuses are described in this paper.
TL;DR: An overview of the underlying principles of AJP are summarized, applications of the technology are reviewed, and where gains may be realised are hypothesised through this assistive manufacturing process.
Abstract: Aerosol Jet Printing (AJP) is an emerging contactless direct write approach aimed at the production of fine features on a wide range of substrates. Originally developed for the manufacture of electronic circuitry, the technology has been explored for a range of applications, including, active and passive electronic components, actuators, sensors, as well as a variety of selective chemical and biological responses. Freeform deposition, coupled with a relatively large stand-off distance, is enabling researchers to produce devices with increased geometric complexity compared to conventional manufacturing or more commonly used direct write approaches. Wide material compatibility, high resolution and independence of orientation have provided novelty in a number of applications when AJP is conducted as a digitally driven approach for integrated manufacture. This overview of the technology will summarise the underlying principles of AJP, review applications of the technology and discuss the hurdles to more widespread industry adoption. Finally, this paper will hypothesise where gains may be realised through this assistive manufacturing process.
TL;DR: In this paper, advances in polyaniline-based ammonia detection sensors are summarized, with a special focus on progresses in polymer modification techniques to achieve enhanced sensing performance, including template synthesis, interfacial and high dilution syntheses, multifunctional dopants, template synthesis and self-oxidizing template synthesis.
Abstract: Recently, there is an increasing interest in ammonia sensing and detection for a wide range of applications, including food, automotive, chemical, environmental, and medical sectors. A major challenge is to obtain selective, sensitive and environmentally stable sensing polymer/chemical materials that can meet the stringent performance requirements of these application areas. Among various polymer-based sensing materials, polyaniline has emerged as a preferred choice owing to its cost-effectiveness, facile preparation steps, and superior sensing performance towards ammonia. In this review, advances in polyaniline based ammonia detection sensors are summarized, with a special focus on progresses in polyaniline modification techniques to achieve enhanced sensing performance. These techniques utilize interfacial and high dilution syntheses, multifunctional dopants, template synthesis, self-oxidizing template synthesis, etc. , methods. Most up-to-date developments in combining polyaniline with other ammonia sensing materials, including polyaniline nanocomposites with metal oxides, graphene, carbon nanotubes and other carbon nanomaterials, are included. These novel nanocomposites have special capabilities of forming p - n nanojunctions or electron interphase interactions for superior detection sensitivity and selectivity. In addition, existing challenges toward understanding, reproducing, and optimizing the design of polyaniline based ammonia sensors are discussed.
TL;DR: A resistive-type flexible ammonia (NH3) sensor was proposed and developed in this paper, which was prepared by depositing polyaniline-cerium dioxide (PANI-CeO2) nanocomposite thin film on flexible polyimide (PI) substrate through in-situ self-assembly method.
Abstract: A resistive-type flexible ammonia (NH3) sensor was proposed and developed in this work, which was prepared by depositing polyaniline-cerium dioxide (PANI-CeO2) nanocomposite thin film on flexible polyimide (PI) substrate through in-situ self-assembly method. The effect of CeO2 nanoparticles on the polymerization of aniline was studied by comparing the morphological, structural and chemical features of the pure PANI and PANI-CeO2 nanocomposite, and the dynamic polymerization processes were also recorded and investigated. In this process, an interesting phenomenon was found that the protonation and oxidation degrees of PANI in PANI-CeO2 nanocomposite were improved significantly according to the XPS spectra analysis, which should be ascribed to the synergetic oxidation of CeO2 nanoparticles and ammonium persulfate (APS). Meanwhile, the NH3-sensing performances of the pure PANI and PANI-CeO2 film sensors were evaluated at room temperature (∼25 °C), which showed that the PANI-CeO2 film sensor possessed enhanced response, reduced recovery time, perfect response-concentration linearity, good reproducibility, splendid selectivity, remarkable long-term stability, ultra-low detectable concentration (16 ppb) and theoretical detection limit (0.274 ppb), and outstanding flexibility without significant response decrease after 500 bending/extending cycles. It was speculated that the excellent sensing performances should probably benefit from the gas-sensing enhancement effect of p-n junction, the improved protonation degree and modified morphology of PANI by the addiction of CeO2 nanoparticles. And, the high flexibility might originate from the flexible structure of PANI chains, and the good adhesion and nano-mechanical performance of PANI-CeO2 film. Besides, the effect of relative humidity on the sensing properties of PANI-CeO2 film sensor was also discussed and analyzed. Therefore, the proposed high-performance flexible PANI-CeO2 thin film sensor holds great promise for application into hand-held or wearable electronic devices for trace-level NH3 detection at room temperature.
TL;DR: A review on the recent development of printed gas sensors can be found in this article, where a variety of gas sensing materials including metal oxides, conducting polymers, carbon nanotubes and two-dimensional (2D) materials are discussed.
Abstract: The rapid development of the Internet of Things (IoT)-enabled applications and connected automation are increasingly making sensing technologies the heart of future intelligent systems. The potential applications have wide-ranging implications, from industrial manufacturing and chemical process control to agriculture and nature conservation, and even to personal health monitoring, smart cities, and national defence. Devices that can detect trace amounts of analyte gases represent the most ubiquitous of these sensor platforms. In particular, the advent of nanostructured organic and inorganic materials has significantly transformed this field. Highly sensitive, selective, and portable sensing devices are now possible due to the large surface to volume ratios, favorable transport properties and tunable surface chemistry of the sensing materials. Here, we present a review on the recent development of printed gas sensors. We first introduce the state-of-the-art printing techniques, and then describe a variety of gas sensing materials including metal oxides, conducting polymers, carbon nanotubes and two-dimensional (2D) materials. Particular emphases are given to the working principles of the printing techniques and sensing mechanisms of the different material systems. Strategies that can improve sensor performance via materials design and device fabrication are discussed. Finally, we summarize the current challenges and present our perspectives in opportunities in the future development of printed gas sensors.
TL;DR: A stretchable temperature sensor consisting of cellular graphene/polydimethylsiloxane composite, the first of its kind, graphene-based polymer composites with desired microstructures with direct 3D ink-writing technique, finds that all three cellular composites present more stable sensitivities than solid composites under external strains.
Abstract: Materials possessing exceptional temperature sensitivity and high stretchability are of importance for real-time temperature monitoring on three-dimensional components with complex geometries, when operating under various external deformation modes. Herein, we develop a stretchable temperature sensor consisting of cellular graphene/polydimethylsiloxane composite. The first of its kind, graphene-based polymer composites with desired microstructures are produced through a direct 3D ink-writing technique. The resultant composites possess long-range-ordered and precisely controlled cellular structure. Temperature-sensing properties of three cellular structures, including grid, triangular, and hexagonal porous structures are studied. It is found that all three cellular composites present more stable sensitivities than solid composites under external strains because of the fine porous structure that can effectively share the external strain, and the composites with a grid structure delivered particularly a stable sensing performance, showing only ∼15% sensitivity decrease at a large tensile strain of 20%. Taking full advantage of the composites with a grid structure in terms of sensitivity, durability, and stability, practical applications of the composite are demonstrated to monitor the cooling process of a heated tube and measure skin temperature accompanying an arbitrary wristwork.