Inkjet-Printed Wireless Chemiresistive Sensors—A Review

Abstract

Microelectronic devices have great potential to be integrated into the Internet of Things, bringing benefits to the environment, society, and economy. Especially, microscaled chemical sensors for environmental monitoring are of great interest since they can be manufactured by cost, time, and resource efficient inkjet printing technology. The aim of the present literature review is a reflection of state-of-the-art inkjet-printed chemiresistive sensors. It examines current material approaches used to realize printed chemiresistors, especially the challenges in the realisation of accurate electrode patterns as well as the deposition of various sensing materials by inkjet printing technology. The review will be completed by an overview of current research activities dealing with the integration of chemiresistive sensors into wireless applications. The result of this review confirms that during the last decades, the number of publications covering inkjet-printed chemical, especially chemiresistive, sensors and their introduction into the Internet of Things is growing. Furthermore, it reveals the need for further research regarding material science and printing technology compatibility to achieve reliable and reproducible chemiresistive sensors.

Advancements in Microfabricated Gas Sensors and Microanalytical Tools for the Sensitive and Selective Detection of Odors

“…Similar to FETs, chemiresistors have been traditionally deployed using metal oxides in the active layer, which normally require high temperatures to operate and contribute to the power consumption of the device ( mW) [ 104 ]. Recent advancements in micromachining techniques (e.g., screen or inkjet printing) have enabled to deploy new nanomaterials on top of chemiresistors (i.e., polymers, carbon structures, or hybrid composites), which operate at room temperature and can offer acceptable sensitivities (e.g., 1–100 ppm) and detection limits in the sub-ppm range (e.g., 800 ppb) [ 105 ]. Moreover, due to the simple and compact design of chemiresistors, these devices can be easily miniaturized and implemented onto flexible substrates, which shows great potential for their implementation in wearable applications [ 106 , 107 ].…”

“…Common purification activities rely on oxidation, the application of high temperature, or washing with acid solutions. CNTs can be then deployed onto target substrates using several techniques, such as drop-casting, electrophoresis, dip coating, or inkjet printing methods [ 105 ]. Despite the good properties of CNTs, they normally come highly entangled by strong van der Waals forces and tend to aggregate, which might compromise their sensing performance [ 171 ].…”

Advanced Characterization Methods for Electrical and Sensoric Components and Devices at the Micro and Nano Scales

“…Summarizing this section, an advanced nanoscale optoelectronic characterization is necessary for emerging device concepts especially from low‐dimensional (1D, 2D) pure, hybrid, and nanoconjugate materials with tailored sensing properties . From the current research, the beneficial sensoric add‐ons comprise, e.g., the spectrally defined optical properties of the active sensing material through photo‐induced electron transfer (PIET) or scattering, their chemical specificity at highest sensitivity, and custom‐oriented fabrication . For optoelectronic sensors, grafting of 1D (nanotubes, nanowires) or 2D (graphene, MoS 2 ) nanomaterials with metal and metal oxide nanoparticles or colloidal semiconductor quantum dots was found to enhance the absorption of carbon‐based materials and to enable high gains .…”

Carbon Nanotubes for Mechanical Sensor Applications

“…Current developments in nanoelectronic technology comprise the integration of individualized CNTs in electronic device platforms. Examples are attempts of CNT‐based logic circuits, sub‐microscale optoelectronic devices comprising photodetectors, emitters, and plasmonic transducers, nanoelectronic sensors for chemical substances, as well as plasmonically assisted detectors of biological molecules …”