Tag: biosensors

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Published chapter in Nanoporous Carbons for Soft and Flexible Energy Devices

LAMPSe was invited to contribute a chapter to the book “Nanoporous Carbons for Soft and Flexible Energy Devices“.

The chapter with the name “Laser-Induced Graphene and Its Applications in Soft (Bio)Sensors” features an overview from formation of LIG, properties to the application in soft (bio)sensors.

Abstract

In recent years the technological importance of graphene increased significantly also in the field of soft, flexible and wearable electronics. In this chapter a simple one step process to create 3D porous graphene structures into flexible polymer films is highlighted. By laser scribing polymer precursor substrates with commercially available laser scribing setups the polymer is converted into so-called Laser-Induced Graphene (LIG) via a photothermal conversion. The properties of this material and the influence of different processing parameters on its composition and structure are introduced. Different transfer methods for stretchable applications are discussed. Three main application fields of LIG for soft (bio)sensors are identified: piezoresistive, electrophysiological and electrochemical sensors. Each of the application fields is highlighted more in detail and an overview of recent publications is given. Concluding with an outlook on the future of LIG – including improvement of patterning resolution and the use of renewable, bio-derived precursors – this chapter provides a broad overview of LIG for soft and flexible sensor devices.

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Paper on Capacitive Coupling of Conducting Polymer Tattoo Electrodes with the Skin

“Capacitive Coupling of Conducting Polymer Tattoo Electrodes with the Skin”

The skin and the electrode interface. a) Schematization of the skin layers. The epidermis, with the stratum corneum as top layer and the electrodes adopted in the study: tattoo and Ag/AgCl electrodes. The dermis, with sweat glands, nerve ending and blood vessels. The subcutaneous tissue, composed by the hypodermis and the muscle layer. On the top-right, the equivalent circuit is adopted to model the skin. b) The electrode/skin interface through Ag/AgCl (top) and tattoo electrode (down). The equivalent circuits are represented together with the physical mechanism leading to the biosignal transduction.

Laura M. Ferrari, Usein Ismailov, Francesco Greco, Esma Ismailova
Publication Date: July 10, 2021
https://onlinelibrary.wiley.com/doi/10.1002/admi.202100352

 

Abstract

Tattoo electronics is one of the emerging technologies in skin compliant biosensing. The growing interest in their large application in health monitoring raises several interrogations on how these sensors interface with the skin. In this paper, the bioimpedance at the interface of the skin and ultra-conformable tattoo electrodes made of conducting polymers are focused on. The electrochemical characteristics of these electrodes differ from traditional gelled Ag/AgCl electrodes. The modeling of equivalent circuits in different skin-electrode configurations proposes the explanation of the biopotentials transduction mechanism. The strong agreement between the circuit model and experimental values reveals the capacitive coupling of conducting polymer tattoo electrodes where circuit’s values reflect the electrodes’ and skin physical characteristics. Additional studies underline an enhanced signal stability in inter/intra-subject evaluations using dry tattoos beneficial for broad long-term recordings. This study provides a comprehensive explanation of the skin/tattoo electrode interface model. The understanding of this interface is essential when designing next generation wearable biomonitoring devices using imperceptible interfaces.

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News Publications

Review on Laser Induced Graphene and its use for Chemical Sensing – Open Access Paper

“Three-Dimensional (3D) Laser-Induced Graphene: Structure, Properties, and Application to Chemical Sensing“

LIG for Chemical sensors review summary

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.