This talk will discuss how OLEDs technology lends itself favorably for all-optical neural interfaces. Following careful development and optimization of processing and passivation routines, my team has very recently succeeded in producing pixelated organic micro-LED arrays that allow to control neuronal activity with unprecedented local specificity. These devices rely on CMOS backplanes that are systematically optimized for efficient and robust contact with OLEDs deposited on top. They also make use of our recent development of thin film encapsulation which allows operation and storage of the devices in water and in biological tissue. Exploratory work with collaborators on the application of the devices in vivo will be discussed.

Cephalopods (e.g., squids, octopuses, and cuttlefish) have captivated the imagination of both the general public and scientists alike due to their sophisticated nervous systems, complex behavioral patterns, and visually stunning camouflage displays. Given their unique capabilities and characteristics, it is not surprising that these marine invertebrates have emerged as exciting models for novel adaptive optical and photonic materials. Within this context, our laboratory has developed various cephalopod-derived and cephalopod-inspired systems with dynamic functionalities within the visible and infrared regions of the electromagnetic spectrum. These findings hold implications for next-generation biomedical imaging technologies and adaptive camouflage devices.

Solution-processed quantum dots are promising building blocks for next-generation optoelectronic devices due to their low-cost, wide tunable bandgap and solution-processibility. Phase transfer ligand exchange has been demonstrated as a promising method to prepare small-size (diameter < 3.5 nm) PbS QDs for device fabrication. However, two obstacles limit the conventional phase transfer ligand exchange method for large-size PbS QDs: densely packed organic shells and charge-neutral (100) surfaces. In this talk, we describe a new strategy providing high-quality large size PbS QD via phase transfer ligand exchange. We use lead acetate trihydrate (PbAc2·3H2O) as a precursor reducing the steric hindrance from the densely packed organic shells, which facilitates the ligand exchange. In addition, we use methylammonium acetate (MAAc) as an additive in PbI2 ligand solution forming perovskite intermediate (MAPbI2Ac) on the (100) surface, which improves the surface passivation. The resulting photodiodes using these large-size QDs without further post-treatment exhibit a near-unity internal quantum efficiency in the short wavelength infrared region.

Near-infrared (NIR) organic photodetectors with high detectivity are fabricated with an organic electron blocking layer (EBL) with an appropriate energy band alignment. To avoid damage to a preceding organic electron blocking layer during a subsequent coating of an organic photoactive layer, cross-linking technology using a novel photoinitiator is used for an EBL. Poly-TPD is used as an EBL due to its appropriate energy band alignment with an NIR organic sensitizing layer. A ternary blend film composed of PTB7-Th, COi8DFIC, and PC71BM are used as a NIR sensitizing layer with strong photosensitivity in multi-spectral (UV-Visible-NIR) wavelengths of 300-1,000 nm.

We report on a ternary blend of SEBS, the donor polymer poly(3-hexylthiophene-2,5-diyl), and the small-molecule acceptor Indene-C60 bisadduct that yields an elastomeric bulk-heterojunction (e-BHJ) with skin-like mechanical properties. This is, with low Young’s moduli < 10 MPa and a high strain at break ca. 190%. We also demonstrate that stretchable e-BHJ enables stretchable organic photodiodes with measured median root-mean-squared electronic noise values in the tens of femtoampere range and measured noise equivalent power values at 653 nm between 13 and 24 pW at strain values up to 60%, yielding specific detectivity values in the 100 Giga-Jones range.

This talk will present the designs of polymeric upconversion imagers that combine photo-sensing and display in a compact structure, to enable infrared visualization to 1300 nm. The organic photodetectors are further improved by incorporating a new heterojunction interlayer to trigger trap-assisted photomultiplication. The interlayer served to suppress the dark current and enhance the photoresponse. The large active area of 2 square cm enabled demonstrations such as object inspection, imaging through smog, and concurrent recording of blood vessel location and blood flow pulses.

Metal-organic frameworks (MOFs) are promising materials for next-generation gas sensing technologies. The implementation of MOFs into scalable gas sensor designs is, however, challenging due to high demands on the MOF film quality. Here, we report the highly sensitive detection of volatile organic compounds by transducing the gas adsorption in MOF thin films, prepared by chemical vapor deposition (MOF-CVD), into surface plasmon polariton shifts. Resonances as sharp as 14 nm, record-breaking shifts larger than 150 nm upon methanol uptake, and a limit of detection below 1 ppm are shown. These findings demonstrate the potential of MOF-CVD thin films for future gas sensing concepts.

To meet the needs of high end gas sensing applications, new materials in suitable device designs are required that can challenge the state-of-the-art, especially concerning affinity towards target compounds within a complex background. Due to their high specific surface area and tailorable pore interiors, metal-organic frameworks (MOFs) serve as promising candidates to function as active coatings in next-generation sensors. However, studies on their integration in optoelectronic devices are rare due to the lack of suitable deposition methods. In this work, photonic crystal sensors functionalized with MOF thin films, are fabricated through a cleanroom-compatible process. The devices are capable of detecting low concentrations of volatile organic compounds, and thus, enable new avenues towards scalable fabrication and integration of miniature MOF-based gas sensor arrays.

Metallic nanogaps are fundamental components of nanoscale photonic and electronic devices. However, the lack of reproducible, high-yield fabrication methods with nanometric control over the gap-size is hindering practical applications. In this presentation, I will describe a novel technique called adhesion lithography that permits the rapid fabrication of nanogap electrodes, with electrode spacings as low as 3 nm. The procedure—which can be carried out at room temperature under ambient conditions, using simple equipment and only a few processing steps—provides a rapid and well-controlled route to a wide range of nanogap devices. I will describe how the basic technique may be combined with other lithographic methods to create large-area (> 1 cm2) arrays that contain hundreds of millions of size-controlled metallic nanogaps, and will give selected examples of how the resulting arrays may be applied in the fields of molecular electronics, plasmonics and biosensing.

We present a fully printed temperature array yielding a total of 625 sensor pixel on a 12 mm by 12 mm area. Screen and aerosol jet printing are combined to fabricate the sensor stack. The active area features a bottom and top silver electrode sandwiching a thermoplastic based thermistor material. Due to the robust behavior towards humidity no encapsulation or special treatment was necessary. The sensor was operated between 0°C to 110°C exhibiting measurement accuracy of +/- 1°C. As demonstration, a laser was used to heat the sensor array locally and its beam properties and diameter could be observed.

Studying how healthy and ailing bodies move in the world around them can inform medical care. One approach towards developing solution-processable pressure sensors with high sensitivity for bio-mechanical sensor applications is to utilize hybrid organic-inorganic hybrid halometallates as the force sensing materials. Halometallates have the formula AmBnXm+n, where A is an organic cation, B is a metal cation, and X is a halide anion. Here, we describe the screening and discovery of novel piezoelectric hybrid halometallates, which turn force into an electric charge, and their mechanical properties in both single crystal and thin film form are described.

The ultrasensitive measurement of protein markers plays a pivotal role in the early diagnosis of infectious and progressive diseases. Recently, digital methods such as those enabled by the Simoa Planar Array technology (SP-X System) have made significant progress in reaching ultrasensitive detection with clinically relevant protein biomarkers. The elicited Simoa technology is based on the printing of high-density capturing antibodies layers on the bottom of the wells of a microtiter plate, followed by a standard sandwich-type immunometric chemiluminescent detection. The elicited assay, reaching limit-of-detections (LODs) in the low femtomolar range, can be conveniently customized via the immobilization of the capturing antibodies. This is accomplished through a pair of anchoring peptide tags printed on the bottom of each well. An optimized Simoa SP-X assay for detecting and quantifying immunoglobulin M (IgM, non-specific indicator of inflammation) is developed herein and optimized. A full factorial experimental design has been undertaken to optimize the assay, leading to a reduced experimental effort and increased quality of the information obtained concerning the traditional one-variable-at-a-time approach. The optimization process leads to an IgM LOD of 4 fM, that compares well with those achieved with commercially available Simoa® Planar Array kits. Remarkably, depositing both the capturing and detecting layer from a solution (0.1 g/mL) one order of magnitude less concentrated than in standard kits is needed, the assay's cost will be sizably reduced.

The talk describes a bio-inspired approach to design and prepare proton conducting materials based on self-assembling short protein sequences (peptides). I will discuss proton transport mechanisms and design principles to improve the conductivity of these materials. I will then demonstrate post assembly processes to tune the proton conductivity further. Finally, I will show materials' stability, biocompatibility, and biodegradability and emphasize the effects of peptide sequence design on these properties. These studies demonstrate the remarkable opportunities of using artificial proteins in developing a new generation of sustainable electronic materials.

The brain can perform massively parallel information processing while consuming only ~1- 100 fJ per synaptic event. I will describe an electrochemical neuromorphic device that switches at low energy (~80 fJ), and displays a large number of distinct, non-volatile conductance states within a ~1 V operating range. The tunable resistance behaves very linearly, allowing blind updates in a neural network when operated with the proper access device. These devices also display outstanding endurance achieving over 109 switching events with very little degradation. I will describe our recent efforts at scaling and materials selection, allowing us to reach 20 ns write pulses and operation at high temperature (up to 120°C). In particular, we developed a fully lithographic process that allowed us to demonstrate sub-µm channel devices, opening the door to integration with Si driving circuitry. By carefully deuterating the electrolytes, we provide strong evidence that the secret to the high speed and low energy switching properties of these artificial synapses is the combination of electronic and protonic transport. Finally, we demonstrate that the working mechanism is quite general by fabricating and operating high-performance synapses based on MXenes. This generality is promising in terms of monolithic integration as MXenes can be chosen to be BEOL compatible with Si.

Despite tremendous research efforts, treatment options for many neurological disorders are inadequate. Systemic drug treatments suffer from side effects and long-term habituation; electrical stimulation is unspecific; and the fluidic injection of drugs often displaces the very cells that are being targeted due to the local pressure increase. Thus, there exists a pressing need to develop novel treatment strategies that overcome these limitations. One such technology is the recently introduced drug delivery platform known as the microfluidic ion pump (µFIP). The µFIP is an implantable device that electrophoretically pumps ions (eg. neurotransmitters, drugs, etc) to the target tissue. In addition to spatial and temporal control, a distinctive feature of the µFIP is that it delivers just the ion and not the solvent and thus does not increase pressure at the outlet. This “dry” delivery is of paramount importance for neural interfacing as it enables an intimate interface between the drug delivery outlet and the target cells. Here we report recent advances in µFIPs and related drug delivery device concepts for treating neurological disorders with a focus on material developments and limitations as well as progress toward clinical applications.

As our understanding of the brain’s physiology and pathology progresses, increasingly sophisticated technologies are required to advance discoveries in neuroscience and develop more effective approaches to treating neuropsychiatric disease. To facilitate clinical translation of advanced materials, devices, and technologies, all components of bioelectronic devices have to be considered. Organic electronics offer a unique approach to device design, due to their mixed ionic/electronic conduction, mechanical flexibility, enhanced biocompatibility, and capability for drug delivery. We design, develop, and characterize conformable organic electronic devices based on conducting polymer-based electrodes, particulate electronic composites, high-performance transistors, conformable integrated circuits, and ion-based data communication. These devices facilitate large-scale neurophysiology experiments and have led to discovery of a novel cortical oscillation involved in memory consolidation as well as elucidated patterns of neural network maturation in the developing brain. The biocompatibility of the devices also allowed intra-operative recording from patients undergoing epilepsy and deep brain stimulation surgeries, highlighting the translational capacity of this class of neural interface devices. In parallel, we are developing the high-speed conformable implantable integrated circuits and embedded acquisition and storage systems required to make high channel count, chronic neurophysiological recording from animals and human subjects possible. This multidisciplinary approach will enable the development of new devices based on organic electronics, with broad applicability to the understanding of physiologic and pathologic network activity, control of brain-machine interfaces, and therapeutic closed-loop devices.

Artificial intelligence applications have demonstrated their enormous potential for complex processing over the last decade. However, they are mainly based on digital operating principles while being part of an analogue world. Moreover, they still lack the efficiency and computing capacity of biological systems. Neuromorphic electronics emulate the analogue information processing of biological nervous systems. Neuromorphic electronics based on organic materials have the ability to emulate efficiently and with fidelity a wide range of bio-inspired functions. A prominent example of a neuromorphic device is based on organic mixed conductors (ionic-electronic). Neuromorphic devices based on organic mixed conductors show volatile, non-volatile and tunable dynamics suitable for the emulation of synaptic plasticity and neuronal functions, and for the mapping of artificial neural networks in physical circuits. Finally, small-scale organic neuromorphic circuits enable the local sensorimotor control and learning in robotics.

Organic electrochemical transistors formed by in operando electropolymerization of the semiconducting channel, which we refer to as evolvable OECTs, or EOECTs, are increasingly becoming recognized as a simple and effective implementation of synapses in neuromorphic hardware. We have been developing EOECTs using a new class of water-soluble, single-component, mixed ion-electron conductors based on the 2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)thiophene (ETE) backbone, which has been functionalized on the central thiophene with a hydrophilic sidechain. The aim of this talk is to highlight: the recent advances in understanding the behavior of these molecules, design principles that are useful to consider when developing EOECTs, and interesting algorithms that can be implemented with simple EOECT-based circuits.

The interface between biological cells and non-biological materials has profound influences on cellular activities, chronic tissue responses, and ultimately the success of medical implants and bioelectronic devices. The optimal coupling between cells and materials is mainly based on surface interaction, electrical communication and sensing. In the last years, many efforts have been devoted to engineer materials to recapitulate both the environment (i.e., dimensionality, curvature, dynamicity) and the functionalities (i.e., long and short term synaptic plasticity) of the neuronal tissue to ensure a better integration of the bioelectronic platform and cells. In this scenario, resembling also the composition of the neuronal membrane might be beneficial to reconstitute fluidity and proteins’ arrangement (i.e. synaptic receptors) to further optimize the communication between neuronal cells and in vitro bioelectronic platforms. Here, we explore how supported lipid bilayers(SLBs) can induce different fluidity at the interface and thus modulate the neuronal outgrowth from the polarity phase to synaptic formation. Moreover, those neuronal SLBs have been achieved also on 3D dendritic-like spines to further recapitulate the composition and the peculiar architecture present at synaptic level. Finally, we engineered organic neuromorphic devices with neuronal SLBs to achieve a biohybrid interface with tunable short term plasticity. In turn, this could represent a first step toward in vitro adaptive neurohybrid interfaces to engineering neuronal networks with biomimetic structural and functional connections at synaptic level.

For leveraging wearable technologies to advance precision medicine, personalized and learning-based analysis of continuously acquired health data is indispensable, for which neuromorphic computing could provide the most efficient implementation of artificial intelligence (AI) data processing. For realizing on-body neuromorphic computing, skin-like stretchability is required to be combined with the suite of desired neuromorphic metrics. In this talk, I will introduce our research in developing new electronic materials, device designs, and fabrication processes for imparting intrinsic stretchability onto neuromorphic devices that can provide state-of-the-art computing performance. I will also show the practical applicability of this device for implementing machine-learning computing and algorithms for health data analysis, when the computing hardware is under human-body-induced deformation.

In vitro cell models have experienced a tremendeous progress over the last decade, as materials, devices and cell culture protocols became the centre of intense research for tissue engineering, drug screening and toxicology assays. While the majority of recently developed microphysiological systems yield sufficient complexity, methods for in situ evaluation of 3D cell cultures in a label-free manner and high-throughput configuration are still limited. We herein demonstrate a novel well plate bioelectronic platform, namely e-transmembrane, capable to support and monitor complex 3D cell architectures. In particular, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) based scaffolds have been engineered to function both as separator membranes for compartmentalized cell cultures, as well as electronic elements for real time and in situ recording of tissue growth and function. Intrinsic limitations arising from the 3D dimensionality of the porous structures are addressed by tailoring the morphological characteristics of the scaffold transmembranes. Impedance spectroscopy measurements carried out throughout the cell culture period, allowed us to identify signatures from different cell types, assessing cell growth and extracting barrier function parameters. Being compatible with current biological standards, we believe that this platform has the potential to become a universal tool for biologists, laying foundation for the next generation of high-throughput drug screening assays.

Hybrid nanogenerator (NG) and Nanosensor (NS), with the blend of triboelectric nanogenerator (TENG) and electromagnetic generator (EMG), has just been demonstrated its productivity in vitality collecting. This examination shows the hybridization of TENG and EMG as a story tile to change over the dynamic vitality of human footfall to electrical vitality. TENG is made out of oppositely charged layers of conductive Aluminum and high- polarized Kapton with electron acceptor MoS2, while EMG (scheme) used Copper loops and Neodymium magnets. The mixture was associated by means of a parallel circuit with a bridge rectifier to guarantee proficient execution, which was estimated with VersaStat300 potentiostat and Tektronix TDS 1001B oscilloscope. The yield arrived at reached 5 mA of short-circuit current and high open-circuit voltage. This crossover nanogenerator produces 25 times more output for a 78% diminishing in the cost of an industrially sold vitality gatherer floor tile. The curiosity of the hybrid NG incorporates its potential for huge scale viable applications in day by day life. In this manner, the energy is converted through a cost-effective and simple nanogenerator to decrease energy expenditures with no negative impacts on nature.

Due to their easy of synthesis and, more importantly, ease of modification organic materials are ideal candidates to explore sensing applications. For electronic detection of many analytes, the sensitivity of the device is typically strongly related to the density of grain boundaries, where the increased surface area and access to the semiconductor / dielectric interface is critical to generating a response. Here, however, our focus is on radiation sensing for both dosimetry and imaging. Here, it is the nature of the materials themselves that determines effectiveness. Improving packing density, and the inclusion of higher-Z elements in the periphery or core of the semiconductor leads to substantial improvements in sensitivity of transistors configured for radiation sensing. The complicated interplay of device configuration and the effect of radiation exposure on the organic device will be discussed. In some situations, less precise information on radiation dose is required, allowing a simple colorimetric approach to be utilized. I will discuss our efforts at controlling sensitivity and packaging for simple, low-cost, colorimetric radiation sensors.

Thiophene-based trimers is a new class of organic electronic molecular units, which enable the organization and polymerization of conjugated structures within living biological systems and inside operating electronic devices and systems. The trimers can be equipped with side groups that targets and promotes coupling to specific surfaces and (bio-)chemical cues making self-organization and -assembly of organic bioelectronics possible in a novel manner. The chemical and physical fundamentals of the trimers, the route of polymerization, and their performance while operating in neuromorphic and in vivo-manufactured bioelectronics will be reported. Specifically, neuromorphic systems based on organic electrochemical transistors including the trimers will be described along with bioelectronic systems formed inside living plants, cells and animal models. Our findings promise for radically new ways of forming bioelectronic systems in living systems, which mimicks the structures and functions of the signaling of biology.