Federico Maria Vivaldi, Alexander Dallinger, Andrea Bonini, Noemi Poma, Lorenzo Sembranti, Denise Biagini, Pietro Salvo, Francesco Greco*, and Fabio Di Francesco*
Publication Date: June 24, 2021
https://pubs.acs.org/doi/10.1021/acsami.1c05614

Abstract

Notwithstanding its relatively recent discovery, graphene has gone through many evolution steps and inspired a multitude of applications in many fields, from electronics to life science. The recent advancements in graphene production and patterning, and the inclusion of two-dimensional (2D) graphenic materials in three-dimensional (3D) superstructures, further extended the number of potential applications. In this Review, we focus on laser-induced graphene (LIG), an intriguing 3D porous graphenic material produced by direct laser scribing of carbonaceous precursors, and on its applications in chemical sensors and biosensors. LIG can be shaped in different 3D forms with a high surface-to-volume ratio, which is a valuable characteristic for sensors that typically rely on phenomena occurring at surfaces and interfaces. Herein, an overview of LIG, including synthesis from various precursors, structure, and characteristic properties, is first provided. The discussion focuses especially on transport and surface properties, and on how these can be controlled by tuning the laser processing. Progresses and trends in LIG-based chemical sensors are then reviewed, discussing the various transduction mechanisms and different LIG functionalization procedures for chemical sensing. A comparative evaluation of sensors performance is then provided. Finally, sensors for glucose detection are reviewed in more detail, since they represent the vast majority of LIG-based chemical sensors.

Bernhard Burtscher, Günther Leising, Francesco Greco
Publication Date: June 10, 2021
https://doi.org/10.1021/acsaelm.1c00249

Abstract

Generation of ultrathin, transferable, and imperceptible electronic devices [e.g., organic photodiode (OPD)] for multiple applications, such as personalized health monitors and wearables, is emerging due to the continuous development of materials and manufacturing processes. For such devices, the choice of a suitable substrate is of utmost importance. A water decal transfer from a temporary tattoo paper is adopted here as a substrate for ultrathin and conformable organic components because of easy and reliable transfer of a ≈600 nm robust and transparent polymer nanofilm of ethyl cellulose. Strategies for the fabrication of a transferable OPD on a temporary tattoo are investigated. A device with an overall thickness <1 μm and its performance after transfer are demonstrated. Then, efforts are put into fabricating an OPD by inkjet printing with a water-soluble active layer consisting of polythiophene and fullerene derivatives to aid cost- and material-efficient, large-scale production possibilities. Additionally, a second semitransparent electrode made of printed aluminum-doped zinc oxide and silver nanowires is used to allow usage from both sides to enhance the application potential. Both OPD examples presented here need improvement of the device performance but permitted us to highlight the versatility and application potential of temporary tattoos for transferable components. Target surfaces for the final application after transfer include artificial (flat and smooth, e.g., glass, or even complex and rough, e.g., concrete, paper, and so forth) as well as natural ones.

Featured in Journal Front COVER of June 2021 Issue

A new open access paper by S. Taccola et al. about skin-contact Temporary Tattoo Electrodes (TTEs). The study is part of a collaboration of our former group at CMBR IIT – Italian Institute of Technology, Pontedera (Italy) with the company MEDEL Gmbh, Innsbruck (Austria). The study investigates skin-contact tattoo electrodes in various bio-electric signals recording applications, such as bioimpedance for respiration monitoring. Novel methods for realizing  a repositionable, long-term stable and robust interconnection of TTEs with external “docking” devices are presented. A further step forward toward the real use of our tattoo interfaces in health monitoring!

Publication  in Sensors MDPI:

Toward the Use of Temporary Tattoo Electrodes for Impedancemetric Respiration Monitoring and Other Electrophysiological Recordings on Skin

Silvia Taccola, Aliria Poliziani,  Daniele Santonocito, Alessio Mondini, Christian Denk, Alessandro Noriaki Ide, Markus Oberparleiter, Francesco Greco, Virgilio Mattoli

Sensors, 21(4), 1197 (2021).

DOI: 10.3390/s21041197
https://www.mdpi.com/1424-8220/21/4/1197

A new paper by Jonathan Barsotti et al. about Organic Light Emitting Diodes (OLEDs) on temporary tattoo. The study is a collaboration with groups of Dr. Virgilio Mattoli (CMBR IIT, Italy) and Prof. Franco Cacialli (UCL, London, UK). Ultrathin tattooable OLEDS are presented which can be transferred onto various target surfaces maintaining their functionality.

Publication  in Advanced Electronic Materials:

Ultrathin, Ultra‐Conformable, and Free‐Standing Tattooable Organic Light‐Emitting Diodes

Jonathan Barsotti, Alexandros G. Rapidis, Ikue Hirata, Francesco Greco, Franco Cacialli, Virgilio Mattoli

Advanced Electronic Materials, 2001145 (2021).

DOI: 10.1002/aelm.202001145
https://onlinelibrary.wiley.com/doi/full/10.1002/aelm.202001145

UPDATE:
The publication on the tattooable OLED got mentioned in the BBC article “Could electric tattoos be the next step in body art?”.

Our contribution to the book:

Chapter 15 – Ultraconformable Organic Electronics

L. M. Ferrari, S. Taccola, J. Barsotti, V. Mattoli,  F. Greco
in Organic Flexible Electronics, Eds. P. Cosseddu, M. Caironi, Elsevier 2021, pages 437-478
Publication Date: October 5, 2020
Link to the Chapter on Science Direct – Elsevier

Here the link to the video available on the YouTube channel of TU Graz:

“Temporary tattoo as unconventional substrate for conformable and transferable electronics on skin and beyond”

Laura M. Ferrari, Kirill Keller, Bernhard Burtscher, Francesco Greco*
Multifunctional Materials, 2020, 3 3.
Published online on July 16, 2020
DOI: 10.1088/2399-7532/aba6e3

Alexander Dallinger, Kirill Keller, Harald Fitzek, Francesco Greco
ACS Appl. Mater. Interfaces, 19855-19865
Publication Date: April 6, 2020
https://doi.org/10.1021/acsami.0c03148

Abstract

The conversion of various polymer substrates into laser-induced graphene (LIG) with a CO₂ laser in ambient condition is recently emerging as a simple method for obtaining patterned porous graphene conductors, with a myriad of applications in sensing, actuation, and energy. In this paper, a method is presented for embedding porous LIG (LIG-P) or LIG fibers (LIG-F) into a thin (about 50 μm) and soft medical grade polyurethane (MPU) providing excellent conformal adhesion on skin, stretchability, and maximum breathability to boost the development of various unperceivable monitoring systems on skin. The effect of varying laser fluence and geometry of the laser scribing on the LIG micro–nanostructure morphology and on the electrical and electromechanical properties of LIG/MPU composites is investigated. A peculiar and distinct behavior is observed for either LIG-P or LIG-F. Excellent stretchability without permanent impairment of conductive properties is revealed up to 100% strain and retained after hundreds of cycles of stretching tests. A distinct piezoresistive behavior, with an average gauge factor of 40, opens the way to various potential strain/pressure sensing applications. A novel method based on laser scribing is then introduced for providing vertical interconnect access (VIA) into LIG/MPU conformable epidermal sensors. Such VIA enables stable connections to an external measurement device, as this represents a typical weakness of many epidermal devices so far. Three examples of minimally invasive LIG/MPU epidermal sensing proof of concepts are presented: as electrodes for electromyographic recording on limb and as piezoresistive sensors for touch and respiration detection on skin. Long-term wearability and functioning up to several days and under repeated stretching tests is demonstrated.