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Metal-dielectric patterned metasurfaces based on fishnet unit cells have been recently proposed as promising platforms for terahertz (THz) Fabry-Perot cavity leaky wave antennas (FPC-LWAs). Still, their experimental validation in the THz range is lacking. In this work, we design several layouts of such metasurfaces at a working frequency of 300 GHz, by varying the geometrical parameters of the unit cell. This variation allows for achieving different electromagnetic responses that in turn provide for different radiating performances when used in a Fabry-Perot cavity environment. For this purpose, we microfabricated eight different demonstrators by patterning a 200-nm aluminum film over a silica substrate through a low-cost, large-area, photolithographic process. The design flexibility of this kind of metasurfaces is then experimentally validated through THz time-domain spectroscopy (TDS) measurements in the reflection mode. The broadband analysis allowed by the used TDS techniques revealed both the simple inductive behavior and the typical dipole resonances of such kind of metasurfaces for the lower part (250–450 GHz) and the higher part (450–650 GHz) of the investigated THz spectrum, respectively. The experimental results were fully consistent with the predictions of both theoretical and full-wave analyses, thus corroborating their efficiency as a means for the design of metasurfaces with controllable THz electromagnetic response, such as the sheet impedance.

We experimentally investigate the photothermal conversion in disordered silicon nanowires (SiNWs) grown on a glass substrate by plasma-enhanced chemical vapor deposition. The temporal and spatial response under illumination of a 532 nm laser has been measured by means of an infrared (IR) thermocamera. Fast heat generation and adjustable temperature increase from a few tens up to ≈600 °C have been observed in a confined small region around the laser spot. The performing photothermal conversion is related to the efficient light trapping in SiNWs, providing enhanced absorption in the visible spectrum, and nonradiative recombination of the photogenerated carriers, typically occurring in Si. These findings combined with a low-cost, low-temperature, and large-area fabrication technology promote the disordered SiNWs as a flexible heat source well suited for applications in multiple fields including biology, precision medicine, gas detection, and nanometallurgy.

Electrocorticography (ECoG) is receiving growing attention for both clinical and research applications thanks to its reduced invasiveness and ability of addressing large cortical areas. These benefits come with a main drawback, i.e. a limited frequency bandwidth. However, recent studies have shown that spiking activity from cortical neurons can be recorded when the ECoG grids present the following combined properties: (I) conformable substrate, (II) small neuron-sized electrodes with (III) low-impedance interfaces. We introduce here an ad-hoc designed ECoG device for investigating how electrode size, interface material composition and electrochemical properties affect the capability to record evoked and spontaneous neural signals from the rat somatosensory cortex and influence the ability to record high frequency neural signal components.Contact diameter reduction down to 8 μm was possible thanks to a specific coating of a (3,4-ethylenedioxytiophene)-poly (styrenesulfonate)-poly-(ethyleneglycol) (PEDOT-PSS-PEG) composite that drastically reduces impedance and increases electrical and ionic conductivities. In addition, the extreme thinness of the polyimide substrate (6 - 8 μm) and the presence of multiple perforations through the device ensure an effective contact with the brain surface and the free flow of cerebrospinal fluid. In-vivo validation was performed on rat somatosensory cortex.

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. Low temperature polycrystalline silicon (LTPS) technology is particularly attractive for such applications, since LTPS TFTs show excellent electrical characteristics, good stability and offer the possibility to exploit CMOS architectures. Then, as examples of flexible sensing systems, we present a tactile sensor for robotic applications and a pH sensor for biomedical applications. 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.

Future system-on-panel applications require further performance improvement of circuits based on polycrystalline silicon thin film transistors (TFTs). The biggest leverage in circuit performance can be obtained by reducing channel length from the typical current values of 3-6 micron to 1 micron, or less. Therefore, short channel effects in scaled down polysilicon TFTs will have to be controlled in order to allow proper operation of the circuits. In this work we review a number of specific aspects of the electrical characteristics of short channel devices (channel lengths down to 0.4 micron) combining electrical characteristics measurements and two-dimensional numerical simulations.

Electrocorticography (ECoG) is receiving growing attention for both clinical and research applications thanks to its reduced invasiveness and ability of addressing large cortical areas. These benefits come with a main drawback, i.e. a limited frequency bandwidth. However, recent studies have shown that spiking activity from cortical neurons can be recorded when the ECoG grids present the following combined properties: (I) conformable substrate, (II) small neuron-sized electrodes with (III) low-impedance interfaces. We introduce here an ad-hoc designed ECoG device for investigating how electrode size, interface material composition and electrochemical properties affect the capability to record evoked and spontaneous neural signals from the rat somatosensory cortex and influence the ability to record high frequency neural signal components.Contact diameter reduction down to 8 μm was possible thanks to a specific coating of a (3,4-ethylenedioxytiophene)-poly (styrenesulfonate)-poly-(ethyleneglycol) (PEDOT-PSS-PEG) composite that drastically reduces impedance and increases electrical and ionic conductivities. In addition, the extreme thinness of the polyimide substrate (6 - 8 μm) and the presence of multiple perforations through the device ensure an effective contact with the brain surface and the free flow of cerebrospinal fluid. In-vivo validation was performed on rat somatosensory cortex.

Glycated albumin (GA) is rapidly emerging as a robust biomarker for screening and monitoring of diabetes. To facilitate its rapid, point‐of‐care measurements, a label‐free surface‐enhanced Raman spectroscopy (SERS) sensing platform is reported that leverages the specificity of molecular vibrations and signal amplification on silver‐coated silicon nanowires (Ag/SiNWs) for highly sensitive and reproducible quantification of GA. The simulations and experimental measurements demonstrate that the disordered orientation of the nanowires coupled with the wicking of the analyte molecules during the process of solvent evaporation facilitates molecular trapping at the generated plasmonic hotspots. Highly sensitive detection of glycated albumin is shown with the ability to visually detect spectral features at as low as 500 × 10−9m, significantly below the physiological range of GA in body fluids. Combined with chemometric regression models, the spectral data recorded on the Ag/SiNWs also allow accurate prediction of glycated concentration in mixtures of glycated and non‐glycated albumin in proportions that reflect those in the bloodstream. A plasmonic nanowire platform for a label‐free and sensitive surface‐enhanced Raman scattering based detection of glycated albumin, a biomarker for screening and monitoring of diabetes. By leveraging molecular trapping at the “nano‐fingers” and in combination with a chemometric regression model, the method enables accurate determination of the amount of glycation in mixture samples.

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. In this review, Benfenati and co‐workers report on the most recent advances on biomaterials (glial) interfaces and devices that enabled to reach unprecedented insights into the role of astroglial cells in brain function and dysfunction. The authors propose Glial interfacing and Glial Engineering as multidisciplinary fields that will potentially allow to extend the knowledge on cognitive functions and neuropathologies.

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. Low temperature polycrystalline silicon (LTPS) technology is particularly attractive for such applications, since LTPS TFTs show excellent electrical characteristics, good stability and offer the possibility to exploit CMOS architectures. Then, as examples of flexible sensing systems, we present a tactile sensor for robotic applications and a pH sensor for biomedical applications. 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.

We found a strong correlation between the layer porosity and electrical properties of a SiO2layer deposited by inductively coupled plasma chemical vapor deposition. At 50 °C the SiO2layers have a double structure: a dense layer in contact with the substrate and a porous layer on top of it. The critical thickness at which voids appear depends on the deposition rate. Breakdown voltage and charge trapping performances of SiO2layers are very good if the thickness is below the critical value and deteriorate significantly in thicker, porous, layers. Layer porosity is absent when the sample is deposited at 250 °C.

We found a strong correlation between the layer porosity and electrical properties of a SiO2 layer deposited by inductively coupled plasma chemical vapor deposition. At 50 degC the SiO2 layers have a double structure: a dense layer in contact with the substrate and a porous layer on top of it. The critical thickness at which voids appear depends on the deposition rate. Breakdown voltage and charge trapping performances of SiO2 layers are very good if the thickness is below the critical value and deteriorate significantly in thicker, porous, layers. Layer porosity is absent when the sample is deposited at 250 degC.

Applications of polycrystalline silicon (polysilicon) thin film transistors (TFTs) to active matrix organic light emitting displays require further performance improvement. The biggest leverage in circuit performance can be obtained by reducing channel length from the typical current values of 3-6μm to 1μm, or less. However, short channel effects and hot-carrier induced instability in scaled down conventional self-aligned polysilicon TFTs can substantially degrade the device characteristics. To reduce these effects and allow proper operation of the circuits, drain field relief architectures have to be introduced. In this work we show that a fully self-aligned gate overlapped lightly doped drain (LDD) structure, with submicron LDD regions, can provide an excellent solution, allowing effective short channel effect control and improved electrical stability.

Future system-on-panel applications require further performance improvement of circuits based on polycrystalline silicon thin film transistors (TFTs). The biggest leverage in circuit performance can be obtained by reducing channel length from the typical current values of 3-6 micron to 1 micron, or less. Therefore, short channel effects in scaled down polysilicon TFTs will have to be controlled in order to allow proper operation of the circuits. In this work we review a number of specific aspects of the electrical characteristics of short channel devices (channel lengths down to 0.4 micron) combining electrical characteristics measurements and two-dimensional numerical simulations.