During the past decade, microelectronics incorporated inkjet-printing technology as a versatile tool for industrial applications, as it combines high printing quality and resolution along with low cost compared to conventional microelectronics techniques that require high cost and complex equipment. In addition, inherently, inkjet printing requires no photolithography steps. In this review paper we present temperature sensors that have been manufactured by inkjet printing. Based on the main active sensing material, the research studies are classified into four different types, i.e. metal and metal oxide-based, carbon-based, polymer-based and composite that combine properties of multiple active materials. It is demonstrated that silver ink has been, by far, the most popular material for metal based temperature sensors with a temperature coefficient of resistance (TCR) of around 2 × 10 ^-3 ◦C ^-1 . Silver sensors as well as almost all metal, carbon and polymer based sensors were either resistance temperature detectors (RTDs) or thermistors. Regarding polymer and carbon-based sensors, it was found that, in some cases, they outperformed metal-based sensors in terms of TCR, although fabrication using such materials had a less predictable result with a TCR ranging from -16 × 10 ^-3 ◦C ^-1 to 2 × 10 ^-3 ◦C ^-1 . Finally, in the case of composite materials as temperature sensors, several combinations of active materials exhibited interesting results and yielded a variety of sensing technologies such as thermocouples and radio frequency based.

Random appearance of micro short circuits and voltage noise is observed, until now, on initial cycles of solid polymer electrolyte high voltage cathode cells with lithium metal anodes. However, this phenomenon also takes place in lower operation voltages such as those in LiFePO₄ cathode cells. Approaching the direct/indirect effect of the cathode, the polymer electrolyte, and the anode parts on this initial dendritic bridging between the electrodes separately, a systematic study is carried out toward determining potential causes of voltage noise and ways of prevention. Electrolytes based on the blend of PMMA–PEO show that relying only on the viscoelastic nature cannot prevent the appearance of voltage noise. Liquid polymers are used for the wetting of the cathode active material that lead to a complete pore infiltration. Having ensured the optimization of the interfacial area between the solid electrolyte and the cathode, studies along the directions of the lithium surface pretreatment and polymer ionic conductivity are examined as a means of dendrite growth suppression and cell cycling capabilities improvement, leading to the observation that methylated PEO chains work in favor of both of these directions.

Silicon nanoparticles are used to enhance the anode specific capacity for the lithium-ion cell technology. Due to the mechanical deficiencies of silicon during lithiation and delithiation, one of the many strategies that have been proposed consists of enwrapping the silicon nanoparticles with graphene and creating a void area between them so as to accommodate the large volume changes that occur in the silicon nanoparticle. This work aims to investigate the electrochemical performance and the associated kinetics of the hollow outer shell nanoparticles. To this end, we prepared hollow outer shell silicon nanoparticles (nps) enwrapped with graphene by using thermally grown silicon dioxide as a sacrificial layer, ball milling to enwrap silicon particles with graphene and hydro fluorine (HF) to etch the sacrificial SiO₂ layer. In addition, in order to offer a wider vision on the electrochemical behavior of the hollow outer shell Si nps, we also prepared all the possible in-between process stages of nps and corresponding electrodes (i.e., bare Si nps, bare Si nps enwrapped with graphene, Si/SiO₂ nps and Si/SiO₂ nps enwrapped with graphene). The morphology of all particles revealed the existence of graphene encapsulation, void, and a residual layer of silicon dioxide depending on the process of each nanoparticle. Corresponding electrodes were prepared and studied in half cell configurations by means of galvanostatic cycling, cyclic voltammetry and electrochemical impedance spectroscopy. It was observed that nanoparticles encapsulated with graphene demonstrated high specific capacity but limited cycle life. In contrast, nanoparticles with void and/or SiO₂ were able to deliver improved cycle life. It is suggested that the existence of the void and/or residual SiO₂ layer limits the formation of rich Li_XSi alloys in the core silicon nanoparticle, providing higher mechanical stability during the lithiation and delithiation processes.

Graphene oxide (GO) is proven to be a very versatile material in sensing devices. As a moisture-sensitive material, it finds a wide variety of applications from biomedical to environmental, which is mainly related to its fast response and low cost. Here a treatment to GO using the metalorganic framework ZIF-8 is applied for the realization and study of humidity sensing. An incremental increase in sensitivity is demonstrated as we move from pure GO to GO blended with ZIF-8 to ZIF-8 dispersed on the GO surface, with two and three order of magnitude change in relative DC current respectively. The particles of ZIF-8 are uniformly dispersed on the GO surface with an average size of 200 nm contributing to ionic conductivity and improving the sensing capabilities. The dynamic analysis reveals that behind the enhanced sensitivity of the surface treated GO lays the fact that, in contrast to GO, the proton ion hopping mechanism kicks in from the lowest relative humidity values and the resistance follows the R~f-1 law throughout the whole relative humidity range, while at the same time it signifies the superficial origin of the sensing mechanism.