Modern societies rely on a multitude of electronic and robotic systems, with emerging stretchable and soft devices enabling ever closer human machine interactions. These advances however take their toll on our ecosystem, with high energy demand, greenhouse gas emission and environmental pollution. Mitigating some of these adverse effects, this talk introduces materials and methods for soft systems that biodegrade. Based on highly stretchable biogels and degradable elastomers, our forms of soft electronics and robots are designed for prolonged operation in ambient conditions without fatigue, but fully degrade after use through biological triggers. Electronic skins provide sensory feedback. Enabling autonomous operation, stretchable and biodegradable batteries are demonstrated that power wearable sweat sensors. 3D printing of biodegradable hydrogels enables omnidirectional soft robots with multifaceted optical sensing abilities. Going beyond, we introduce a systematically-determined compatible materials systems for the creation of fully biodegradable, high-performance electrohydraulic soft actuators. These embodiments reliably operate up to high electric fields, show performance comparable to non-biodegradable counterparts, and survive over 100,000 actuation cycles. Pushing the boundaries of sustainable electronics, we demonstrate a concept for growth and processing of fungal mycelium skins as biodegradable substrate material. Mycelium-based batteries with capacities as high as ~3.8 mAh cm−2 allow to power autonomous sensing devices including a Bluetooth module and humidity and proximity sensors, all integrated onto mycelium circuit boards.

Electrochemiluminescence (ECL) is a phenomenon in which light is emitted from the excited state of a redox-active material generated by electrochemical reactions. ECL devices have various advantages in terms of structure and simple fabrication, and they are therefore expected as next generation emitting devices. In this paper, we report that electrochemically triggered upconverted luminescence through triplet–triplet energy transfer (TTET) and subsequent triplet–triplet annihilation upconversion (TTA-UC) is first observed in the electrochemiluminescence properties of a Ru complex/diphenylantracene (DPA) containing electrochemical device. Further, ultra-fast quick response in emission is observed in DNA modified electrode cell.

Two-dimensional (2D) materials are a class of materials with unique properties that have attracted significant attention in recent years. Unlike 3D materials, which have bulk properties that are governed by their crystal structure, 2D materials have properties that are strongly influenced by their size and shape. Graphene is perhaps the most well known 2D material due to its exceptional properties. Preparation of 2D materials based on organic molecules is a key-point to obtain devices with original photonics functionalities. Herein, we focused on 2D materials based on perylene diimide derivatives. Our main goal was to prepare highly oriented 2D materials while also controlling molecular orientations and intermolecular electronic interactions. The consequences on photonics processes will be presented. Moreover, we report preliminary results on the combination of such materials with graphene. Such systems could constitute building blocks for future innovative metamaterials.

Materials that can change their properties upon exposure to environmental stimuli are gaining an increasing interest, because they enable novel opportunities for the design and the realization of reconfigurable and adaptive objects and devices. The capabilities of these devices can be further enhanced by nanofabrication technologies, which allows complex and miniaturized architectures to be realized. Examples of complex nanostructured materials are polymer nanofibers, which have already found application in many fields including responsive systems [1-4]. In this presentation we will review our recent works aimed at realizing polymer nanofibers whose shape and function can be varied and controlled by external inputs in order to achieve intelligent complex materials. Electrospinning is here exploited for the nanofiber realization. Relevant applications in this framework include optical switching and logics. The research leading to these results has received funding from the Italian Minister of University and Research through the PRIN 201795SBA3, 2017PHRM8X and 20173L7W8K projects.

This conference presentation was prepared for SPIE Security + Defence, 2023

Despite fluorescent sensing is a reference method for the detection of a plethora of different compounds, the exploitation of this class of sensors is still limited to a few application scenarios as a result of the restricted availability of miniaturized, portable, and user-friendly devices. Here, the smart combination of an organic photodiode (OPD), a Distributed Bragg Filter (DBR), and an organic light-emitting diode (OLED) is proven to provide a stacked device architecture capable of detecting fluorescent signals for a wide range of concentrations of “Rhodamine 700” ranging from 10-3 M to 10-6 M.

Within light sensing optoelectronic devices, multijunction organic and hybrid photodetectors show a large potential. In particular, organic and hybrid phototransistors hold promises for high-sensitivity thanks to their inherent signal-amplification characteristics. However, often a trade-off between a large sensing area, a fast response, and a high specific detectivity is difficult to be achieved. Here we propose an alternative phototransistor concept, that relies on a geometrically engineered large area tri-channel architecture, applied to a multilayer hybrid phototransistor composed of an inorganic In2O3/ZnO n-type field-effect channel, and a top organic bulk-heterojunction or hybrid perovskite light-sensing layer. Up-scalable solution-processing of both the field-effect channel and the light-sensing layers are implemented. Different photoactive layers are used to corroborate and validate the proposed concept. The resulting phototransistor combines the characteristics of easy solution processing, a maximum responsivity of 10^5 A/W thanks to the large electron mobility of the In2O3/ZnO heterointerface, and a maximum specific detectivity of 10^15Jones (at a low gate voltage of 5V and under a low light illumination of 10 nW/cm2), thanks to the large sensing area which is fully exploited in the tri-channel architecture. The improved photoresponse characteristics are accompanied by a fast response (risetime <10ms down to the uW/cm2 of illumination), which is comparable to the time-response of analogous phototransistors in the conventional architecture. The experimental data are supported by device modelling, which helps highlighting the peculiar advantages of the proposed large area, tri-channel and multi-junction phototransistor architecture.

Optical biosensors based on plasmonic sensing schemes combine high sensitivity and selectivity with label-free detection. However, the use of bulky optical components is still hampering the possibility of obtaining miniaturized systems required for analysis in real settings [1]. Here, we demonstrate a fully miniaturized optical biosensor prototype based on plasmonic detection that enables fast and multiplex sensing of analytes with high- and low-molecular weight (80000 and 582 Dalton) as quality and safety parameters for milk: a protein (lactoferrin) and an antibiotic (streptomycin). The optical sensor is based on the smart integration of (i) miniaturized organic optoelectronic devices used as light-emitting and -sensing elements and (ii) a functionalized nanostructured plasmonic grating for highly sensitive and specific localized surface plasmon resonance (SPR) detection [2]. The sensor provides quantitative and linear response reaching a limit of detection of 10^-4 refractive index units once it is calibrated by standard solutions. Analyte-specific and rapid (15 minute-long) immunoassay-based detection is demonstrated for both targets. By using a custom algorithm based on principal-component analysis, a linear dose-response curve is constructed which correlated with a limit of detection (LOD) as low as 3.7 μg/mL for lactoferrin, thus assessing that the miniaturized optical biosensor well-aligned with the reference benchtop SPR method [3].

The photoreceptor protein bacteriorhodopsin (bR) has a solar function and is therefore used in sensors that do not require a bias power supply. A position-sensitive detector (PSD) is a monolithic photosensor utilising photodiode surface resistance that can measure a position of a light spot incident on a surface. Compared to discrete element detectors such as CCD/CMOS arrays, PSD provides continuous position measuring and high position resolution. This study presents 1D and 2D PSD based on bR and conductive polymer instead of semiconductors. A bR-polymer-PSD consists of a drop-casted bR film on a thin polymer film and a counter-thick polymer electrode. The nonlinearity of the one-dimensional PSD (light-receiving length 6.0 cm) is 2.3-2.5%, well below the 15% tolerance of semiconductor PSDs, and an all-organic one-dimensional PSD is realised at the cost of about 1/1500 of a semiconductor PSD. Furthermore, a two-dimensional PSD (photosensitive area 3.0 × 3.0 cm2) showed the feasibility of an all-organic two-dimensional PSD at about 1/500. However, the maximum position detection error was insufficient at 20 to 30 %.

Our body is composed by unit blocks: organs, tissues and, ultimately, cells. Understanding the functioning of cells in health and disease, plays a fundamental role for future tissue engineering and drug-discovery applications. However, current cell biology protocols are limited to 2D cultures, which, although inexpensive and easy to handle, do not reproduce the complexity of real tissues. In this talk, I show how to surpass these conventional approaches by realizing biomimetic 3D microstructures for both fundamental cell mechanobiology and in-vitro disease/treatment modeling. The focus will be on the most recent results of our research activity, which exploits laser-assisted 3D printing for the creation of biomimetic microenvironments dedicated to three types of tissue: brain, brain cancer and bone.

Electro-active robotic materials are the interface between the digital world and the physical one. They produce force/motion in response to an electrical stimulus (artificial muscles) and generate electrical signals in response to physical stimuli (soft sensors). Some materials can change their bulk or surface properties responding to a digital input (electro-active and variable stiffness materials). My work has focused on electro-fluidic artificial muscles and electro-active soft grippers. These solid-state soft devices are silent, flexible, and miniaturized. They offer a path towards highly integrated responsive materials for the next generation of intelligent robots and active wearables. In this talk, I will first discuss the force/softness dilemma in soft robotics and how we leverage electro-adhesion on soft fingers to develop grippers that are at the same time delicate enough to pick a ripe tomato and so strong to lift 1000 times their own weight. These grippers can also grasp flexible objects such as fabric and plastic. pouches This technology is now being commercialized by the spin-off company Omnigrasp SRL and is part of two EU-funded projects. I will then present our work on solid-state soft pumps, as a means of using fluids to decouple electrical transducers from mechanical motion, easing material and fabrication requirements. Our solid-state pumps solve the challenge of integrating fluid circulation in soft robots and wearables, replacing noisy and bulk pumps and compressors with stretchable or fiber-shaped pumps. I will conclude discussing future directions for electro-active soft materials.

Here we present additive manufacturing processes (full 3D and 2.5D grayscale modes) to fabricate micro and nano precision optical components for snapshot imaging spectrometers and sensing devices. Specifically we apply 2 Photon Polymerization (2PP) technique to manufacture multifaceted mirrors, arbitrary waveguide/fiber arrays and lenslet array components. All these can be effectively applied in field integral snapshot imaging spectrometers. The fabrication process allows features of 100nm-150nm and surface roughness of 10-20 nm – sufficient for optical quality components. The focus of this presentation is to analyze component designs in context of spatial and spectral sampling, overall part geometry, component performance (throughout, form etc.) and fabrication times. Overall, complete spectrometer dimensions are also discussed in terms of individual element features - unit size (facet, fiber etc.). Presented proof of concept prototypes demonstrate potential for high level integration, small dimensions and design flexibility. Test spectral samples are imaged in VIS spectral range using mapping and fiber array based methods.

Advanced processes towards the design and fabrication of nanophotonic structures have yielded numerous material concepts for customizable light-matter interactions. Tailored sub-wavelength structures of select materials, such as plasmonic metasurfaces and polymeric bragg reflectors, enable strong electromagnetic (EM) interactions that can be tuned to select frequencies across the spectrum. While such systems can be independently tailored towards precise colorimetric outputs in both static and dynamic configurations, new opportunities emerge in hybridized forms that enable more precise spectral control. In this work the processing routes and spectral tunability of metasurface-bragg reflectors will be discussed. Of emphasis is the scalable nature of the fabrication approaches and opportunities to control the hybridized interactions.