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Given the current maturity of printed technologies, Organic Thin-Film Transistors (OTFT) still show high initial variability, which can be beneficial for its exploitation in security applications. In this work, the process-related variability and aging of commercial OTFTs have been characterized to evaluate the feasibility of OTFTs-based Physical Unclonable Functions (PUFs) implementation. For our devices, ID-based PUFs show good uniformity and uniqueness. However, PUFs’ reliability could be compromised because of the observed transient and aging effects in the OTFTs, which could hinder the reproducibility of the generated fingerprints. A systematic study of the aging of OTFTs has been performed to evaluate the PUFs’ reliability. Our results suggest that the observed transient and aging effects could be mitigated so that the OTFTs-based PUFs’ reliability could be improved.

Due to their complex formulation, conductive nanoparticle inks for inkjet printing are limited in terms of the types of metals and substrates that can be utilized. A new and simplified class of inks called metal salt decomposition (MSD) inks has the potential to introduce a multitude of metals, which can be printed directly onto a wide range of substrates. Here, the use of atmospheric oxygen plasma to develop polycrystalline Au and Pt films at processing temperatures near room temperature (≈33 °C) with excellent conductivities up to 105 S m−1 is demonstrated. The conformal nature of the ink allows metal films to be printed onto a broad range of temperature-sensitive substrates including polymers, papers, and fabric. The Au ink is then used to build a simple light-emitting diode circuit showing its flexibility, durability, and long-term stability as deposited thin metal films. Additionally, such inks cost less than one-third the price of similar nanoparticle inks highlighting their overall affordability and good stability.

Altres ajuts: Agència per a la Competitivitat de l'Empresa de la Generalitat de Catalunya by FEDER funds, Institució Catalana de Recerca i Estudis Avançats, and ERDF funds, In this paper, an organic, fully recyclable and eco-friendly 20-bit inkjet-printed chipless RFID tag is presented. The tag operates in the near field and is implemented by means of chains of resonant elements. The characterization and manufacturing process of the tag, printed with a few layers of a commercial organic ink on conventional paper substrate (DIN A4), are presented, and tag functionality is demonstrated by reading it by means of a custom-designed reader. The tags are read by proximity (through the near field), by displacing them over a resonator-loaded transmission line, and each resonant element (bit) of the tag is interrogated by a harmonic signal tuned to the resonance frequency. The coupling between the reader line and the resonant elements of the tag produce and amplitude modulated (AM) signal containing the identification (ID) code of the tag.

Organic and printed electronics (OE) is a promising technology for reducing the waste and the price of electronic systems for new devices. OE offers technological advantages not available in conventional silicon processes such as physical flexibility, large area fabrication, mask-less deposition, low process temperatures and fully additive manufacturing—processes that all enable low-cost and low-waste fabrication techniques. Despite these advantages, important difficulties remain for developing compact models for transistors due to intrinsic variability in the manufacturing process and the behaviour of organic materials, which make it difficult to match the model and the experimental data. Due to disparity in the fabrication methodologies and the different topologies of transistors used, the diversity in compact models is noticeable. These different models provide specific solutions for particular devices and require various process design kits (PDKs) for each manufacturing process. This review covers the different PDKs developed in the OE field and compares them with the electric models used for simulation purposes. Both simulated and fabricated systems are included with the aim of providing the reader with a clear state-of-the-art of the OE situation.

In this paper, an organic, fully recyclable and eco-friendly 20-bit inkjet-printed chipless RFID tag is presented. The tag operates in the near field and is implemented by means of chains of resonant elements. The characterization and manufacturing process of the tag, printed with a few layers of a commercial organic ink on conventional paper substrate (DIN A4), are presented, and tag functionality is demonstrated by reading it by means of a custom-designed reader. The tags are read by proximity (through the near field), by displacing them over a resonator-loaded transmission line, and each resonant element (bit) of the tag is interrogated by a harmonic signal tuned to the resonance frequency. The coupling between the reader line and the resonant elements of the tag produce and amplitude modulated (AM) signal containing the identification (ID) code of the tag.

Near-field chipless-RFID tags with high data density and synchronous reading capability are presented and experimentally validated in this paper. The tags consist of a chain of rectangular patches etched or printed at predefined positions on a dielectric substrate, including rigid or flexible (i.e., plastic or even paper) substrates. Patch dimensions determine the binary state, where the larger and smaller patches are associated with the logic '1' and '0' states, respectively, or vice versa. For sequentially and synchronously reading the bits, a sensitive element able to determine the presence of the patches and their size by proximity (through near field using microwaves) is considered. Such element is a microstrip line loaded with a pair of rectangular complementary split ring resonators (CSRRs), one etched inside the other in the ground plane. When the tag chain is displaced at short distance over the CSRRs, the larger patches modify the resonance frequency of both sensing CSRRs, whereas the lower patches do only alter the resonance frequency of the smaller CSRR. Consequently, the ID code is contained in the patch dimensions, and the presence of a patch (regardless of its size) determines the reading times (clock signal), necessary for synchronous reading. Tag reading in this system proceeds by feeding the CSRR-loaded line (reader) with a pair of harmonic signals tuned to the resonance frequencies of the bare CSRRs. Both signals are amplitude modulated (AM) at the output port as consequence of tag motion, and the respective envelope functions contain both the clock signal and the tag ID code. The ID codes of several 16-bit tags, implemented on different substrates (microwave substrate, plastic and paper) and exhibiting a per unit length density of 1.67 bit/cm, have been inferred with the dedicated reader for validation purposes.

The rise of internet of things (IoTs) applications has led to the development of a new generation of light-weight, flexible, and cost-effective electronics. These devices and sensors have to be simultaneously easily replaceable and disposable while being environmentally sustainable. Thus, the introduction of new functionalized materials with mechanical flexibility that can be processed using large-area and facile fabrication methods (as, for example, printing technologies) has become a matter of great interest in the scientific community. In this context, cellulose nanofibers (CNFs) are renewable, affordable, robust, and nontoxic materials that are rapidly emerging as components for eco-friendly electronics. Their combination with conductive polymers (CPs) to obtain conductive nanopapers (CNPs) allows moving their functionality from just substrates to active components of the device. In this work, a route for the inkjet-printing of organic diodes is outlined. The proposed strategy is based on the use of CNPs as both substrates and bottom electrodes onto which insulator and organic semiconducting layers are deposited to fabricate novel diode structures. Remarkable rectification ratios of up to 1.2 x 10(3) at |3 V| and a current density up to 5.1 mu A cm(-2) are achieved. As a proof-of-concept of the potentiality of the approach for versatile, low-temperature, and disposable sensing applications, an NO2 gas sensor is presented., Funding Agencies|MICIU-Spain [RTI2018-102070-B-C21]; Generalitat de CatalunyaGeneralitat de Catalunya [2017SGR-1159]; FEDER fundsEuropean Union (EU); University of Girona [BTI2018/12]

The demand for real-time monitoring of cell functions and cell conditions has dramatically increased with the emergence of organ-on-a-chip (OOC) systems. However, the incorporation of co-cultures and microfluidic channels in OOC systems increases their biological complexity and therefore makes the analysis and monitoring of analytical parameters inside the device more difficult. In this work, we present an approach to integrate multiple sensors in an extremely thin, porous and delicate membrane inside a liver-on-a-chip device. Specifically, three electrochemical dissolved oxygen (DO) sensors were inkjet-printed along the microfluidic channel allowing local online monitoring of oxygen concentrations. This approach demonstrates the existence of an oxygen gradient up to 17.5% for rat hepatocytes and 32.5% for human hepatocytes along the bottom channel. Such gradients are considered crucial for the appearance of zonation of the liver. Inkjet printing (IJP) was the selected technology as it allows drop on demand material deposition compatible with delicate substrates, as used in this study, which cannot withstand temperatures higher than 130 °C. For the deposition of uniform gold and silver conductive inks on the porous membrane, a primer layer using SU-8 dielectric material was used to seal the porosity of the membrane at defined areas, with the aim of building a uniform sensor device. As a proof-of-concept, experiments with cell cultures of primary human and rat hepatocytes were performed, and oxygen consumption rate was stimulated with carbonyl-cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP), accelerating the basal respiration of 0.23 ± 0.07 nmol s-1/106 cells up to 5.95 ± 0.67 nmol s-1/106 cells s for rat cells and the basal respiration of 0.17 ± 0.10 nmol s-1/106 cells by up to 10.62 ± 1.15 nmol s-1/106 cells for human cells, with higher oxygen consumption of the cells seeded at the outflow zone. These results demonstrate that the approach of printing sensors ins, Peer Reviewed, Postprint (author's final draft)

We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement.

We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement.