Search

Edible electronics is an emerging research field targeting electronic devices that can be safely ingested and directly digested or metabolized by the human body. As such, it paves the way...

The growing demand of disposable electronics raises serious concerns for the corresponding increase in the amount of electronic waste, with severe environmental impact. Organic and flexible electronics have been proposed long ago as a more sustainable and energy-efficient technological platform with respect to established ones. Yet, such technology is leading to a drastic increase of plastic waste if common approaches for flexible substrates are followed. In this scenario, biodegradable solutions can significantly limit the environmental impact, actively contributing to eliminate the waste streams (plastic or electronic) associated with disposal of devices. However, achieving suitably scalable processes to pattern mechanically robust organic electronics onto largely available biodegradable substrates is still an open challenge. In this work, all-organic and highly flexible field-effect transistors, inkjet printed onto the biodegradable and compostable commercial substrate Mater-Bi, are demonstrated. Because of the thermal instability of Mater-Bi, no annealing steps are applied, producing devices with limited carrier mobility, yet showing correct n-type behavior and robustness to bending and crumpling. The degradation behavior of the final system shows unaltered biodegradability level according to ISO 14851. These results represent a promising step toward sustainable flexible and large-area electronics, combining energy and materials efficient processes with largely available biodegradable substrates.

Organic electronics has been steadily evolving, with improving performances, including unrivaled mechanical properties. One of the main technological trends aims at thinner and lighter form factors, toward the realization of ultraflexible and conformable large-area electronic devices, capable of withstanding harsh mechanical stresses and therefore finding applications where rigid or brittle technologies would fail. Pursuing this objective, a critical role is known to be played by the substrate, whose thickness needs to be reduced as much as possible while maintaining its processability. Ultrathin substrates and a neutral plane strategy have therefore been exploited to realize ultrathin organic devices; however, ultraflexible complementary circuits based on printed organic semiconductors, realized by means of high-throughput and large-area techniques, have not been realized so far. In this work, all-polymer organic field effect transistors and complementary inverters have been printed onto a micrometer-thin parylene substrate, subsequently also used as a top isolation layer in order to place the active components in the neutral plane of stresses. These devices show appropriate low voltage operation, with supply voltages as low as 2 V, and retain stable and uniform performances upon the application of harsh mechanical stresses, such as rolling and crumpling. These results represent the first demonstration of semi-transparent and fully organic crumpable printed electronics, and pave the way toward the realization of more complex complementary logic circuits, laying the foundation for their widespread and cost-effective integration into consumer products.

Biosensors are expected to revolutionize disease management through provision of low-cost diagnostic platforms for molecular and pathogenic detection with high sensitivity and short time-to-result. In this context, there has been an ever-increasing interest in using electrolyte-gated field-effect transistors (EG-FETs) for biosensing applications owing to their expanding potential of being employed for label-free detection of a broad range of biomarkers with high selectivity and sensitivity while operating at sub-volt working potentials. Whereas organic semiconductors have been widely utilized as the channel in EG-FETs primarily due to their compatibility with cost-effective low-temperature solution-processing fabrication techniques, alternative carbon-based platforms have the potential to provide similar advantages with improved electronic performances. Here we propose the use of inkjet-printed polymer-wrapped monochiral single-walled carbon nanotubes (s-SWCNT) for the channel in EG-FETs in an aqueous environment. In particular, we show that our EG-CNTFETs require only an hour of stabilization before producing a highly stable response suitable for biosensing, with a drastic time reduction with respect to the most exploited organic semiconductor for biosensors. As a proof-of-principle, we successfully employed our water-gated device to detect the well-known biotin-streptavidin binding event.

The increasing diffusion of portable and wearable technologies results in a growing interest in electronic devices having features such as flexibility, lightness-in-weight, transparency, and wireless operation. Organic electronics is proposed as a potential candidate to fulfill such needs, in particular targeting pervasive radio-frequency (RF) applications. Still, limitations in terms of device performances at RF, particularly severe when large-area and scalable fabrication techniques are employed, have largely precluded the achievement of such an appealing scenario. In this work, the rectification of an electromagnetic wave at 13.56 MHz with a fully inkjet printed polymer diode is demonstrated. The rectifier, a key enabling component of future pervasive wireless systems, is fabricated through scalable large-area methods on plastic. To provide a proof-of-principle demonstration of its future applicability, its adoption in powering a printed integrated polymer circuit is presented. The possibility of harvesting electrical power from RF waves and delivering it to a cheap flexible substrate through a simple printed circuitry paves the way to a plethora of appealing distributed electronic applications.

Despite their great potentiality, ISFET-like devices generally suffer from an intrinsic limitation in sensitivity, the so-called Nernst limit. Moreover, the high costs, the restricted range of employable materials associated to the silicon technology, and the need for a reference electrode, have reduced the applicability of such devices in the bio-sensing field. In this work, we show how a reference-less pH sensor based on an organic semiconductor device, called Organic Charge-Modulated Field-Effect Transistor (OCMFET), besides being low cost, flexible, and transparent, shows a super-nernstian sensitivity with no need of any chemical modification of the sensing area. Moreover, thanks to its peculiar transduction principle and structure, the device sensitivity can be easily tuned by acting on geometry-related parameters of the device itself, introducing an interesting alternative approach for the realization of highly sensitive, reference-less, and low-cost devices for a wide range of bio-sensing applications.

Organic bioelectronic sensors based on an electrolyte gated field-effect transistor are gaining momentum due to their extraordinary high-performance level that enables label-free selective single-molecule detection of both genomic and protein biomarkers with a millimeter-wide electrolyte-gated field-effect transistor (EGOFET) device. The organic semiconductor channel material used so far is a spin-coated regio-regular poly(3-hexylthiophene) (P3HT). Of paramount importance is to design an EGOFET sensor that is stable and cost-effective. To address the latter feature, an ink-jet printed regio-regular P3HT film is here investigated as the channel material. Moreover, the EGOFET device structure is intended to comprise a coplanar lateral gate electrode that enables mechanical and electrical stability. Overall, the structure is compatible with large area processing so it can be fabricated at low-costs and can be operated continuously for eight days. Additionally, systematic optical and Raman characterization of the P3HT film proves that the printing process results in a film with a low energetic disorder (better π–π stacking in the crystalline regions) that likely enables stable operation. However, the higher quality crystalline regions (as compared to a spin-coated film) are dispersed in a more significant fraction of the amorphous disordered material with a larger amount of trap states. The higher crystalline order is ascribed to the higher boiling point and slower evaporation of the ortho-dichlorobenzene solvent used in the printing process. Overall, the present study provides a systematic insight into the structure–property correlations, essential to design a well-functioning and cost-effective EGOFET for high-performance electronic biosensing. It also provides one of the few investigations comparing the features characterizing a spin-coated and an ink-jet printed P3HT film.

Charge Modulated OTFTs represent a versatile tool for the realization of a wide range of sensing applications. The architecture is based on a floating gate organic transistor whose sensitivity to a specific target is obtained by properly functionalizing a part of the floating gate with a sensing layer that can be chosen according to the specific external stimulus to be sensed. In this work we will show that such devices can be routinely fabricated on highly flexible, ultra-conformable thin films and that they can be employed, with no need of any chemical modification of the sensing area, for monitoring pH variations featuring a super-nernstian sensitivity. Interestingly, we will also show that the proposed approach has been applied for monitoring cell metabolic activity, demonstrated with a preliminary validation. In addition this device can be used for monitoring electrical activity of excitable cells, thus giving rise to a new family of highly sensitive, reference-less, and low-cost devices for a wide range of bio-sensing applications. Finally, we will also demonstrate that using a different sensing layer it is possible to employ the same device architecture for the realization of matrices of multimodal tactile transducers capable to detect at the same time temperature and pressure stimuli, and that being fabricated on sub-micrometer thin film can be conformably transferred on whatever kind of surface allowing the reproduction of the sense of touch.

Correction for ‘Printed, cost-effective and stable poly(3-hexylthiophene) electrolyte-gated field-effect transistors’ by Davide Blasi et al., J. Mater. Chem. C, 2020, DOI: 10.1039/d0tc03342a.

This paper reports on a highly sensitive tactile sensor based on a floating gate organic transistor called Organic Charge Modulated FET coupled with a flexible piezoelectric polymer (namely a film of polyvinylene fluoride, PVDF). The proposed device is able to reliably transduce pressures as low as 300 Pa, thus opening up interesting perspectives for flexible and low-cost tactile sensors for e-skin applications.

In this work, we introduce a novel approach for the fabrication of temperature sensors. The devices are based on the integration of an Organic Charge Modulated Field Effect Transistor (OCMFET) with a pyroelectric polymeric element. Thanks to the optimization of the gate dielectric structure the fabricated sensors can be operated at very low voltages, and moreover, are fabricated on highly flexible plastic substrates. The results demonstrate that the sensors are able to detect in a very reproducible way, temperature variations from 20 °C up to 50 °C. This architecture represents a simple and innovative solution for the realization of conformable sensing systems for applications in tactile sensing as well as in wearable electronics.

In this letter, we report a novel approach for the fabrication of temperature sensors on highly flexible plastic substrates that can be operated at low voltage. Reproducible temperature sensors have been obtained by coupling a charge-modulated organic field-effect transistor with a pyroelectric element. An accurate electrical characterization shows that these devices, because of the local amplification of the organic transistor, can reliably detect temperatures in the range 10 °C-40 °C. This architecture represents a simple and innovative solution for the realization of conformable sensing systems for applications in tactile sensing as well as in wearable electronics.