This paper reports the design, the microfabrication and the experimental characterization of an ultra-thin narrow-band metamaterial absorber at terahertz frequencies. The metamaterial device is ...composed of a highly flexible polyimide spacer included between a top electric ring resonator with a four-fold rotational symmetry and a bottom ground plane that avoids misalignment problems. Its performance has been experimentally demonstrated by a custom polarization-maintaining reflection-mode terahertz time-domain spectroscopy system properly designed in order to reach a collimated configuration of the terahertz beam. The dependence of the spectral characteristics of this metamaterial absorber has been evaluated on the azimuthal angle under oblique incidence. The obtained absorbance levels are comprised between 67% and 74% at 1.092 THz and the polarization insensitivity has been verified in transverse electric polarization. This offers potential prospects in terahertz imaging, in terahertz stealth technology, in substance identification, and in non-planar applications. The proposed compact experimental set-up can be applied to investigate arbitrary polarization-sensitive terahertz devices under oblique incidence, allowing for a wide reproducibility of the measurements.
4‑aminophenol (pAP) is a typical secondary product obtained in pharmaceuticals preparation that needs to be accurately measured to avoid dangerous collateral effects in drugs. According to European, ...United States and Chinese Pharmacopoeias authorities the level of pAP in drugs is limited to 50 ppm. Therefore, it is crucial to define suitable methods to fabricate innovative devices for a fast and accurate detection of these molecules. To this purpose, a strategy is presented combining fast detection methods such as Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and Chronoamperometry taking advantage of the nanostructured electrodes' properties. In this work, we propose a simple and novel electrochemical sensor based on nanostructured electrode comprised of ZnO nanorods decorated by bimetallic (AuxPt1−x) Clusters. To finely tune the composition and the size of the metal nanoclusters we used a Laser Ablation Cluster Beam Deposition technique (LACBD) thus obtaining nanoparticle with an average size of 2–3 nm. Different composition in the AuxPt1-x clusters (with x = 0, 0.5, 1) have revealed specific sensing capabilities. In particular, Au/ZnO electrodes did not show a significant improvement respect to the bare ZnO electrode. Conversely, Pt/ZnO electrodes showed a higher sensitivity (12.55 μA/mM cm2) and a limit of detection of 4.1 μM while Au0.5Pt0.5/ZnO electrodes resulted the best combination, exhibiting sensitivity of 14.31 μA/mM cm2 and a limit of detection of 3.6 μM.
Research over the past four decades has highlighted the importance of certain brain cells, called glial cells, and has moved the neurocentric vision of structure, function, and pathology of the ...nervous system toward a more holistic perspective. In this view, the demand for technologies that are able to target and both selectively monitor and control glial cells is emerging as a challenge across neuroscience, engineering, chemistry, and material science. Frequently neglected or marginally considered as a barrier to be overcome between neural implants and neuronal targets, glial cells, and in particular astrocytes, are increasingly considered as active players in determining the outcomes of device implantation. This review provides a concise overview not only of the previously established but also of the emerging physiological and pathological roles of astrocytes. It also critically discusses the most recent advances in biomaterial interfaces and devices that interact with glial cells and thus have enabled scientists to reach unprecedented insights into the role of astroglial cells in brain function and dysfunction. This work proposes glial interfaces and glial engineering as multidisciplinary fields that have the potential to enable significant advancement of knowledge surrounding cognitive function and acute and chronic neuropathologies.
A Swallowable Smart Pill for Local Drug Delivery Goffredo, Rosa; Pecora, Alessandro; Maiolo, Luca ...
Journal of microelectromechanical systems,
2016-April, 2016-4-00, 20160401, Letnik:
25, Številka:
2
Journal Article
Recenzirano
In this paper, a smart pill for local drug delivery is presented. The pill is designed to achieve local therapy on gastrointestinal tissue thanks to a novel drug delivery system (DDS). The DDS ...consists of a miniature electrolytic pump. This microfabricated pump is ideal for medical applications because of its low power consumption, compatibility with small size batteries, integrability on miniaturized systems, and biocompatibility. The actuation principle of the micropump relies on the electrolysis of a water-based solution, which is separated from a drug reservoir by an elastic membrane. The electrolytically produced gases pressurize the electrolytic solution reservoir, causing the deflection of the elastic membrane. Such deflection, in turn, forces the drug out of its reservoir through a nozzle. In order to measure and monitor the membrane displacement, and therefore the volume of drug ejected, a strain gauge sensor has been prepared using a conductive thermoplastic nanocomposite elastomer (CTPE). The sensor is fixed on the deformable membrane. The CTPE shows high sensitivity and allows to customize the resistance of the device to obtain low power consumption. Thus, by measuring the current though the electrolytic cell and monitoring membrane deformation, the volume of the ejected drug can be controlled.
The understanding of brain processing requires monitoring and exogenous modulation of neuronal ensembles. To this end, it is critical to implement equipment that ideally provides highly accurate, low ...latency recording and stimulation capabilities, that is functional for different experimental preparations and that is highly compact and mobile. To address these requirements, we designed a small ultra-flexible multielectrode array and combined it with an ultra-compact electronic system. The device consists of a polyimide microelectrode array (8 µm thick and with electrodes measuring as low as 10 µm in diameter) connected to a miniaturized electronic board capable of amplifying, filtering and digitalizing neural signals and, in addition, of stimulating brain tissue. To evaluate the system, we recorded slow oscillations generated in the cerebral cortex network both from in vitro slices and from in vivo anesthetized animals, and we modulated the oscillatory pattern by means of electrical and visual stimulation. Finally, we established a preliminary closed-loop algorithm in vitro that exploits the low latency of the electronics (<0.5 ms), thus allowing monitoring and modulating emergent cortical activity in real time to a desired target oscillatory frequency.
Flexible sensors are gaining increasing interest in a number of applications, including biomedical, food control, domotics and robotics, having very light weight, robustness and low cost. In order to ...improve signal-to-noise ratio, integration of readout electronics is crucial and several technologies are available for the fabrication of thin film transistors (TFTs) based circuits on flexible substrates. Among these technologies, the low temperature polycrystalline silicon (LTPS) is particularly attractive, since LTPS TFTs show excellent electrical characteristics, good stability and offer the possibility to exploit CMOS architectures. The different aspects for the direct fabrication of LTPS TFTs on polymer substrates are reviewed and the specific fabrication process adopted on ultrathin polyimide substrates is described in some detail. Then, as examples of flexible sensing systems, we present both chemical and physical sensors integrated with LTPS TFTs frontend electronics. The present results can pave the way to advanced flexible sensing systems, where sensors and local signal conditioning circuits can be integrated on the same flexible substrate.
Flexible electronics has emerged as a promising field for the development of electronic devices with applications in wearables, biomedical sensors, and edible electronics. Biomaterials play a crucial ...role in fabricating flexible substrates, and the utilization of polymer blends offers exciting possibilities for tuning mechanical and chemical properties. This paper highlights the potential of a novel polymer blend based on ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) in the fabrication of substrates for flexible electronics. By blending the two cellulose ethers, it is possible to tune the mechanical and chemical properties of the final substrate, tailored to meet specific requirements. To exploit such innovative green substrates for photolithographic processes, their stability, and processability is extensively investigated. The feasibility of photolithographic processes on such biodegradable and edible substrates is demonstrated by fabricating both resistive and capacitive sensors through standard photolithographic processes, presenting a breakthrough in terms of applicability. The utilization of such biomaterials holds tremendous potential for driving technological advancements in various fields. These materials pave the way for innovative devices catering to diverse applications, from agriculture to food and biomedicine. Importantly, they also promote a sustainable approach for their fabrication, laying the foundation for an environment‐aware future of technological progress.
This paper explores the potential of a novel polymer blend, ethyl cellulose (EC) and hydroxypropyl cellulose (HPC), in flexible electronics. The blend allows for the tuning of mechanical and chemical properties of substrates, demonstrated through resistive and capacitive sensor fabrication via photolithography. These biomaterials offer sustainable and versatile options for advancements in various fields.
The direct integration of disordered arranged and randomly oriented silicon nanowires (SiNWs) into ultraflexible and transferable electronic circuits for electrochemical biosensing applications is ...proposed. The working electrode (WE) of a three-electrode impedance device, fabricated on a polyimide (PI) film, is modified with SiNWs covered by a thin Au layer and functionalized to bind the sensing element. The biosensing behavior is investigated through the ligand-receptor binding of biotin-avidin system. Impedance measurements show a very efficient detection of the avidin over a broad range of concentrations from hundreds of micromolar down to the picomolar values. The impedance response is modeled through a simple equivalent circuit, which takes into account the unique WE morphology and its modification with successive layers of biomolecules. This approach of exploiting highly disordered SiNW ensemble in biosensing proves to be very promising for the following three main reasons: first, the system morphology allows high sensing performance; second, these nanostructures can be built via scalable and transferable fabrication methodology allowing an easy integration on non-conventional substrates; third, reliable modeling of the sensing response can be developed by considering the morphological and surface characteristics over an ensemble of disordered NWs rather than over individual NWs.
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