Conjugated Polymers for Microwave Applications: Untethered Sensing Platforms and Multifunctional Devices.

In the past two decades, organic electronic materials have enabled and accelerated a large and diverse set of technologies, from energy-harvesting devices and electromechanical actuators, to flexible and printed (opto)electronic circuitry. Among organic (semi)conductors, organic mixed ion-electronic conductors (OMIECs) are now at the center of renewed interest in organic electronics, as they are key drivers of recent developments in the fields of bioelectronics, energy storage, and neuromorphic computing. However, due to the relatively slow switching dynamics of organic electronics, their application in microwave technology, until recently, has been overlooked. Nonetheless, other unique properties of OMIECs, such as their substantial electrochemical tunability, charge-modulation range, and processability, make this field of use ripe with opportunities. In this work, the use of a series of solution-processed intrinsic OMIECs is demonstrated to actively tune the properties of metamaterial-inspired microwave devices, including an untethered bioelectrochemical sensing platform that requires no external power, and a tunable resonating structure with independent amplitude- and frequency-modulation. These devices showcase the considerable potential of OMIEC-based metadevices in autonomous bioelectronics and reconfigurable microwave optics.

Preparation of Naphthalene Dianhydride Bithiophene Copolymers by Direct Arylation Polycondensation and the Latent Pigment Approach.

An alternating naphthalene dianhydride bithiophene copolymer (PNDAT2) is prepared by a combined direct arylation polycondensation and the latent pigment approach. PNDAT2 is the first reported example of an alternating conjugated polymer containing naphthalene dianhydride, the oxo-analogue of naphthalene diimide often used in electron-acceptor conjugated polymers. PNDAT2 is resistant to organic solvents and can be generated directly as film by thermal treatment of the soluble tetraester precursor PNTET2. PNDAT2 is characterized by a LUMO level of -3.9 eV, similar to that of established naphthalene diimide containing soluble copolymers. This route to insoluble electron acceptor copolymers by thermal cleavage of soluble precursors is an alternative to classical cross-linking or orthogonal processing strategies.

Preparation of Naphthalene Dianhydride Bithiophene Copolymers by Direct Arylation Polycondensation and the Latent Pigment Approach.

Invited for this month's cover are the collaborating groups of Prof. Luca Beverina from the University of Molani-Bicocca, Italy and Prof. Michael Sommer from Chemnitz University of Technology, Germany. The front cover shows the thermally induced transformation of a soluble and electron-rich naphthalene tetraester-bithiophene copolymer into the corresponding insoluble and electron-poor naphthalenetetraanhydride derivative. The combination of monochromatic squares, inspired by the work of Josef Albers, shows the color change involved in the transformation. Read the full text of the article at 10.1002/cplu.201900210.

Real-Time Monitoring of Cellular Cultures with Electrolyte-Gated Carbon Nanotube Transistors.

Cell-based biosensors constitute a fundamental tool in biotechnology, and their relevance has greatly increased in recent years as a result of a surging demand for reduced animal testing and for high-throughput and cost-effective in vitro screening platforms dedicated to environmental and biomedical diagnostics, drug development, and toxicology. In this context, electrochemical/electronic cell-based biosensors represent a promising class of devices that enable long-term and real-time monitoring of cell physiology in a noninvasive and label-free fashion, with a remarkable potential for process automation and parallelization. Common limitations of this class of devices at large include the need for substrate surface modification strategies to ensure cell adhesion and immobilization, limited compatibility with complementary optical cell-probing techniques, and the need for frequency-dependent measurements, which rely on elaborated equivalent electrical circuit models for data analysis and interpretation. We hereby demonstrate the monitoring of cell adhesion and detachment through the time-dependent variations in the quasi-static characteristic current curves of a highly stable electrolyte-gated transistor, based on an optically transparent network of printable polymer-wrapped semiconducting carbon-nanotubes.

Tattoo-Paper Transfer as a Versatile Platform for All-Printed Organic Edible Electronics.

The use of natural or bioinspired materials to develop edible electronic devices is a potentially disruptive technology that can boost point-of-care testing. The technology exploits devices that can be safely ingested, along with pills or even food, and operated from within the gastrointestinal tract. Ingestible electronics can potentially target a significant number of biomedical applications, both as therapeutic and diagnostic tool, and this technology may also impact the food industry, by providing ingestible or food-compatible electronic tags that can "smart" track goods and monitor their quality along the distribution chain. Temporary tattoo-paper is hereby proposed as a simple and versatile platform for the integration of electronics onto food and pharmaceutical capsules. In particular, the fabrication of all-printed organic field-effect transistors on untreated commercial tattoo-paper, and their subsequent transfer and operation on edible substrates with a complex nonplanar geometry is demonstrated.