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.
Although its first definition dates back to more than a century ago, pH and its measurement are still studied for improving the performance of current sensors in everyday analysis. The gold standard is the glass electrode, but its intrinsic fragility and need of frequent calibration are pushing the research field towards alternative sensitive devices and materials. In this review, we describe the most recent optical, electrochemical, and transistor-based sensors to provide an overview on the status of the scientific efforts towards pH sensing.
Quality and safety of the cold chain undergo strict international regulations that identify storage and shipping temperatures. In fact, the improper handling and transportation of temperature-sensitive products such as food and pharmaceuticals may have harmful effects on human health and a negative economic impact. A passive RFID tag modified with a copper-doped ionic liquid was used to detect the crossing of a temperature threshold (8 °C) during the shipping of medical products. The tag was insensitive to humidity variations and irreversibly changed its status once temperature exceeded the ionic liquid melting point, which can be tuned by changing the concentration of dopant.
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