Laser‐induced graphene (LIG) can be obtained by irradiation of a polymer by a laser source. The present work demonstrates that it is possible to obtain this kind of material using an ultraviolet laser instead of the typical infrared source. Using this approach, a fourfold decrease in the penetration depth (5 µm) is achieved, while the spatial resolution is doubled. Electromechanical strain LIG sensors are patterned in polyimide substrates with different thicknesses and their performance to strain, bending, and force inputs is measured. A low‐cost arterial pulse wave monitor is built, exploring the high force sensitivity of the sensors produced on the thinner substrates.

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For analytical applications in portable sensors to be used in the point-of-need, low-cost SERS substrates using paper as a base, are an alternative. In this work, SERS substrates were produced on two different types of paper: a high porosity paper (Whatman no. 1); and a low porosity paper (commercially available office paper, Portucel Soporcel). Solutions containing spherical silver nanoparticles (AgNPs) and silver nanostars (AgNSs) were separately drop-casted on hydrophilic wells patterned on the papers. The porosity of the paper was found to play a determinant role on the AgNP and AgNS distribution along the paper fibres, with most of the nanoparticles being retained at the illuminated surface of the office paper substrate. The highest SERS enhancements were obtained for the office paper substrate, with deposited AgNSs. A limit of detection for rhodamine-6G as low as 11.4 ± 0.2 pg could be achieved, with an analytical enhancement factor of ≈107 for this specific analyte. The well patterning technique allowed good signal uniformity (RSD of 1.7%). Besides, these SERS substrates remained stable after 5 weeks of storage (RSD of 7.3%). Paper-induced aggregation of AgNPs was found to be a viable alternative to the classical salt-induced aggregation, to obtain a highly sensitive SERS substrates.

Electrochemically active bacteria (EAB) have the capability to transfer electrons to cell exterior, a feature that is currently explored for important applications in bioremediation and biotechnology fields. However, the number of isolated and characterized EAB species is still very limited regarding their abundance in nature. Colorimetric detection has emerged recently as an attractive mean for fast identification and characterization of analytes based on the use of electrochromic materials. In this work, WO3 nanoparticles were synthesized by microwave assisted hydrothermal synthesis and used to impregnate non-treated regular office paper substrates. This allowed the production of a paper-based colorimetric sensor able to detect EAB in a simple, rapid, reliable, inexpensive and eco-friendly method. The developed platform was then tested with Geobacter sulfurreducens, as a proof of concept. G. sulfurreducens cells were detected at latent phase with an RGB ratio of 1.10 ± 0.04, and a response time of two hours.

display backplanes and creating multifunctional flexible circuitry with thin-film technologies are considered. Within this scenario, amorphous oxide semiconductor (AOS) became one of the most competitive TFT technologies, enabling excellent uniformity in large areas, high transparency in visible spectrum, and field-effect mobility (µ FE ) exceeding 10 cm 2 V −1 s −1 even when fabricated below 200 °C. [1][2][3] The potential of these materials as semiconductors in TFTs started to be recognized in 2004 with the work by Nomura et al. on flexible indium-gallium-zinc oxide (IGZO) transistors. [4] Despite the establishment of IGZO TFTs as a key technology for large-area electronics, indium and gallium are critical raw materials, imposing important constrains regarding the sustainability of this approach. [5] Therefore, the ideal route for the next-generation AOS-based transistor technology should comprise an indium-and gallium-free semiconductor material, providing at least comparable performance and processing temperature to IGZO. Zinc-tin oxide (ZTO) has been recognized as a likely choice. Chiang et al. [6] reported in 2005 the first successful integration of sputtered ZTO as semiconductor layer in TFTs. Their staggered bottom-gate, top contact devices showed µ FE ≈ 20-50 cm 2 V −1 s −1 , turn-on voltage (V on ) between −5 and 5 V, and on/off ratio > 10 7 when annealed at 600 °C. However, µ FE drastically decreased to 5-15 cm 2 V −1 s −1 when lower annealing temperature (300 °C) was used, which is still too high for temperature-sensitive polymeric substrates as polyethylene naphthalene (PEN). Since then more than 150 articles on ZTO TFTs have been published, following both physical and solution-processing routes. Focusing on sputtering, which is the processing technique with easier penetration on an industrial TFT baseline process, aspects as different Zn:Sn ratios, [7][8][9] chamber pressure, oxygen flow ratio, and RF power during sputtering have been studied. [10] Nonetheless, for all these experiments a processing or post-processing temperature exceeding 300 °C was always used to achieve proper device operation (e.g., µ FE > 5 cm 2 V −1 s −1 in devices properly patterned, where overestimation of mobility due to fringing effects can be neglected. [11] A very recent work by Han et al. [12] is the exception to this, where a remarkable saturation mobility (µ sat ) of 67 cm 2 V −1 s −1 is achieved for polycrystalline tin-doped Zinc-tin oxide (ZTO) is widely invoked as a promising indium and galliumfree alternative for amorphous oxide semiconductor based thin-film transistors (TFTs). The main bottleneck of this semiconductor material compared to mainstream indium-gallium-zinc oxide (IGZO) is centered in the larger processing temperatures required to achieve acceptable performance (>300 °C), not compatible with low-cost flexible substrates. This work reports for the first time flexible amorphous-ZTO TFTs processed at a maximum temperature of 180 °C. Different aspects are explored to obtain performance levels comparable ...

Organolead halide perovskites have drawn significant attention from the scientific community as one of the most attractive materials in optoelectronics, especially in the field of photovoltaics. In this study, we focus on using halide perovskites in processing thin film transistors (TFTs). Halide perovskites have high solution processability and excellent carrier transport characteristics, in particular for holes. The present work aims to fill a gap in oxide-based technology. It concerns the process of using high-stable and reliable p-type oxide-based devices to target CMOS technology (complementary metal-oxide-semiconductor). We report on a solutionprocessed high-performance TFT based on methylammonium lead iodide (CH 3 NH 3 PbI 3 ) perovskite semiconductor films, which shows promise for devices that can be simple to manufacture with high reliability, reproducibility, and excellent stability in atmospheric conditions. To achieve a highly stable perovskite semiconductor film, we introduce diethylsulfide in the perovskite precursor. The TFT shows a stable p-type behavior when operated at low voltages (≤−2 V) and has a current modulation of >10 4 , an almost negligible hysteresis, and average saturation mobility of about 18.8 cm 2 V −1 s −1 , taken over 50 devices tested (the highest one measured was ∼23.2 cm 2 V −1 s −1 ). This is the highest value until now reported in the literature. In addition, we demonstrate that perovskite TFTs can be fabricated at temperatures as low as 150 °C on flexible substrates with a saturation mobility of ∼11.5 cm 2 V −1 s −1 . The high-performance perovskite TFT with excellent stability is a promising candidate for the next generation of p-type transistors for a plethora of low-cost electronics applications. KEYWORDS: CH 3 NH 3 PbI 3 perovskite, stability, thin film transistor, p-type halide perovskite, mobility, flexible transistor

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Breast cancer accounts for 11.6% of all cancer cases in both genders. Even though several diagnostic techniques have been developed, the mostly used are invasive, complex, time-consuming, and cannot guarantee an early diagnosis, significantly constraining the tumor treatment success rate. Exosomes are extracellular vesicles that carry biomolecules from tissues to the peripheral circulation, representing an emerging noninvasive source of markers for early cancer diagnosis. Current techniques for exosomes analysis are frequently complex, time-consuming, and expensive. Raman spectroscopy interest has risen lately, because of its nondestructive analysis and little to no sample preparation, while having very low analyte concentration/volume, because of surface enhancement signal (SERS) possibility. However, active SERS substrates are needed, and commercially available substrates come with a high cost and low shelf life. In this work, composites of commercial nata de coco to produce bacterial nanocellulose and in-situ-synthesized silver nanoparticles are tested as SERS substrates, with a low cost and green approach. Enhancement factors from 104 to 105 were obtained, detecting Rhodamine 6G (R6G) concentrations as low as 10–11 M. Exosome samples coming from MCF-10A (nontumorigenic breast epithelium) and MDA-MB-231 (breast cancer) cell cultures were tested on the synthesized substrates, and the obtained Raman spectra were subjected to statistical principal component analysis (PCA). Combining PCA with Raman intravariability and intervariability in exosomal samples, data grouping with 95% confidence was possible, serving as a low-cost, green, and label-free diagnosis method, with promising applicability in clinical settings.