25 research outputs found
Graphene as an active material for sensors and other devices
No full textL'abstract è presente nell'allegato / the abstract is in the attachmen
Recurrent Neural Network Model for On-Board Estimation of the Side-Slip Angle in a Four-Wheel Drive and Steering Vehicle
No full textA valuable quantity for analyzing the lateral dynamics of road vehicles is the side-slip angle, that is,
the angle between the vehicle’s longitudinal axis and its speed direction. A reliable real-time side slip angle value enables several features, such as stability controls, identification of understeer and
oversteer conditions, estimation of lateral forces during cornering, or tire grip and wear estimation.
Since the direct measurement of this variable can only be done with complex and expensive devices,
it is worth trying to estimate it through virtual sensors based on mathematical models. This article
illustrates a methodology for real-time on-board estimation of the side-slip angle through a machine
learning model (SSE—side-slip estimator). It exploits a recurrent neural network trained and tested
via on-road experimental data acquisition. In particular, the machine learning model only uses input
signals from a standard road car sensor configuration. The model adaptability to different road
conditions and tire wear levels has been verified through a sensitivity analysis and model testing on
real-world data proves the robustness and accuracy of the proposed solution achieving a root mean
square error (RMSE) of 0.18 deg and a maximum absolute error of 1.52 deg on the test dataset. The
proposed model can be considered as a reliable and cheap potential solution for the real-time
on-board side-slip angle estimation in serial cars
A contamination-free electrolyte-gated organic transistors platform for high-accuracy tumor biomarker detection
No full textA novel biosensor platform for high-accuracy tumor biomarker detection exploiting contamination free microfluidics for increasing the signal-to-noise ratio has been successfully developed and tested. Electrolyte-gated organic Transistors (EGOT) has been employed to detect an important tumor marker, Angiopoietin-2 (Ang2). Although organic semiconductors have become popular in the last years in biosensing applications due to their many advantages, there is still a main concern about stability and selectivity. This work presents major improvement in terms of the stability and selective detection of Ang2 in the range of interest for biomedical applications. The semiconducting polymer poly[3-(5-carboxypentyl)thiophene (P3CPT) is deposited by picoliter volume control and micrometer diameter of the droplet to allow for high uniformity and repeatability from sample to sample. The optimized gold electrodes improve the detection of the minimal concentration of the target and microfluidic interfacing by a specific pattern with the desired dimensions is obtained by UV-lithography and wet etching. A microfluidics with multiple flow control allows for maintain a constant fresh solution without analytes on reference gate electrode, while another inlet and functionalized gate is used for sensing, thus reaching high stability and reproducibility. All these (four) optimizations lead to new measuring protocol and new 3D printed top cover that ensure better stabilization and repeatability of the results. The device has successfully detected Ang2 concentrations as low as 10 pM in saline, therefore demonstrating the ability of the device to detect clinically relevant concentrations
A novel electrolyte gated graphene Field Effect Transistor on Cyclo Olefin Copolymer foil
No full textIn this work an electrolyte gated Graphene field effect transistor (G-FET) has been developed exploiting a Hot-embossing assisted technique to transfer Single Layer Graphene (SLG) on a Cyclo Olefin Copolymer (COC) foil. An investigation on the processing and materials related effects has been carried out by a comparison with a more traditional Poly(methyl methacrylate) (PMMA) transfer approach. The fabricated G-FETs were tested as pH sensors and the electrical characteristics were investigated
Design of a Portable Microfluidic Platform for EGOT-Based in Liquid Biosensing
No full textIn biosensing applications, the exploitation of organic transistors gated via a liquid electrolyte has increased in the last years thanks to their enormous advantages in terms of sensitivity, low cost and power consumption. However, a practical aspect limiting the use of these devices in real applications is the contamination of the organic material, which represents an obstacle for the realization of a portable sensing platform based on electrolyte-gated organic transistors (EGOTs). In this work, a novel contamination-free microfluidic platform allowing differential measurements is presented and validated through finite element modeling simulations. The proposed design allows the exposure of the sensing electrode without contaminating the EGOT device during the whole sensing tests protocol. Furthermore, the platform is exploited to perform the detection of bovine serum albumin (BSA) as a validation test for the introduced differential protocol, demonstrating the capability to detect BSA at 1 pM concentration. The lack of contamination and the differential measurements provided in this work can be the first steps towards the realization of a reliable EGOT-based portable sensing instrument
Recyclability of ceramic powder in CerAM vat photopolymerization
No full textThe sustainability of the manufacturing industry is becoming an increasingly hot topic, particularly the reintroduction of waste into the production chain. The use of AM of ceramics can reduce waste and enable complex,
lightweight designs, however, practical routes to circularity remain underdeveloped. This investigation aims to
explore the potential of coupling these additive fabrication techniques with raw materials from alternative
sources of ceramics, such as printing wastes and error prints, developing a photocurable ceramic suspension for
DLP technology. For resin preparation, a polymeric premix was first prepared by combining a mixture of
different acrylate monomers as a photoreactive binder with a non-reactive plasticizing additive. Alumina was
recovered from failed green bodies following matrix burning out, parts grinding and sieving of the obtained
powder. Subsequent investigations of the powder by SEM imaging and EDX analysis were carried out to verify
particle morphology and average dimensions and to identify any contaminants in the recycled material. The
suspension viscosity and curing behaviour were measured. Finally, the mechanical characteristics of printed
parts, their density, their shrinkage, as well as possible contaminants, were evaluated, in order to understand the
impact of the recycling process on material performances and to determine its possible application fields. Tests
results provided a practical recycling potential for alumina in DLP, offering viable solutions in facilitating closedloop CerAM manufacturing
The fabrication of Schottky photodiode by monolayer graphene direct-transfer-on-silicon
No full textA two-step hot embossing process was used to transfer graphene and to fabricate Gr/Si Schottky photodiodes. As a direct graphene transfer technique through a hot embossing system, chemical vapor deposition Gr monolayer was transferred from copper foil to cyclic olefin copolymer foil without a poly(methylmethacrylate) sacrificial layer. Then, hot embossing was employed once again to bond graphene with the prepared Si substrate to form Schottky contact. Electrical and photoelectrical characterizations have been performed to evaluate the Schottky photodiode. The photocurrent increases linearly with light intensity under 633 nm illumination. With an appropriate bias voltage, the maximum responsivity reaches 0.73 A/W. Extracted from I–V characteristics by Cheung’s function, the Schottky barrier height and ideality factor are 1.01 eV and 2.66, respectively. The experimental result shows the feasibility and effectiveness of this hot embossing fabrication process, which demonstrates the opportunity for large scale production and provides a new approach for graphene optoelectronics
P3HT Processing Study for In-Liquid EGOFET Biosensors: Effects of the Solvent and the Surface
No full textIn-liquid biosensing is the new frontier of cells real time monitoring and biomarkers detection. In order to improve the stability and electrical properties of an Electrolyte Gated Organic Field Effect Transistor (EGOFET) biosensor, in this study we investigate the effect of the solvent and of the substrate modification on thin films of organic semiconductor Poly(3-hexylthiophene) (P3HT). The studied surface is the relevant interface between the P3HT and the electrolyte acting as gate dielectric for in-liquid detection of an analyte. AFM and XPS characterizations were employed to study the effect of two solvents (toluene and 1,2-dichlorobenzene) and of the adhesion promoter (Ti prime) on the morphological structure and electronic properties of P3HT film. Combining the results from the surface characterizations with electrical measurements, we investigate the changes on the EGOFET performances and stability in DI water with an Ag/AgCl gate electrode
Investigation and Modeling of the Electrical Bias Stress in Electrolyte‐Gated Organic Transistors
No full textPDAC-on-chip for in vitro modeling of stromal and pancreatic cancer cells crosstalk
No full textPancreatic ductal adenocarcinoma (PDAC) mainly develops in the head of the pancreas, within the acinoductal unit composed of acinar and ductal cells surrounded by pancreatic stellate cells (PSCs). PSCs strongly influence the tumor microenvironment by triggering an intense stromal deposition, which plays a key role in tumor progression and limits drug perfusion. We have developed a microfluidic in vitro model recreating the in vivo tumor-stroma crosstalk to replicate the steps of PDAC evolution towards the establishment of an efficient in vitro platform for innovative therapy validation. The multilayer PDAC-on-chip was designed to culture the PDAC cells and the PSCs embedded in a type I collagen gel in the top and bottom layers, respectively. The presence of a biomimetic nanofibrous membrane in the middle of the chip permits the control of interactions between the two cell lines and the easy analysis of the effects of the crosstalk on cell behavior. First, the PDAC-stromal cell relationship was evaluated under co-culture conditions on 24-well inserts including the PCL/Gel electrospun membrane. This simplified model shows that human fibroblasts change their morphology and secrete larger amounts of IL-6 cytokines in the presence of tumor cells, confirming the activation of stromal cells under co-culture. Then, the PDAC-on-chip system was validated by demonstrating that human fibroblasts seeded in a 3D collagen matrix in the bottom microchannel also change to a myofibroblast-like shape with increased expression of α-SMA and secrete larger amounts of IL-6 cytokines. This microfluidic system is suitable for the evaluation of drug efficacy and serves as a powerful tool for understanding the early evolution steps of PDAC
