Nanomechanical sensors have been expected as a promising platform for many fields owing to their high versatility; almost any kind of materials can be applied as receptor layers. Among various types of nanomechanical sensors, recently developed Membrane-type Surface stress Sensor (MSS) has attracted much attention as a new platform for mobile and/or Internet of Things (IoT)-based applications because it realizes both high sensitivity and a compact system at the same time. This article introduces the development process of MSS and its working principle with basic/technical details.

Artificial olfaction is a technology that stays beyond our reach for decades because odors are highly complex mixture of gases, and the odor itself fluctuates in terms of time and space. Owing to the development of various innovative technologies in recent years, artificial olfaction is getting about to enter in range of the practical implementation. The receptor material has a key role to detect and/or discriminate the complex gases of versatile odors. In this chapter, we introduce the promising sensor system, “Membrane-type Surface stress Sensor (MSS),” especially about the developments of its receptor materials. In addition, we also introduce possible applications using advanced receptor materials.

We introduce a method to extract quantitative information of liquid samples from their smells which are complicated gaseous mixture consisting of diverse molecules. The highly accurate estimation of the quantitative information was achieved by the effective combination of a nanomechanical sensor (MSS), functional nanoparticles, and machine learning. As a demonstration, the alcohol content of various liquors was successfully quantified by the present approach. Furthermore, we also introduce the concentration extraction of each component in ternary liquid mixtures which are composed of water, ethanol, and methanol.

Not only a sensor itself but also a data processing method for sensing signals is an essential issue for realizing a practical artificial olfactory sensor. In this article, we explain data processing methods which utilize the concept of control engineering. We show some of the recent studies using membrane-type surface stress sensors (MSS) analyzed with the new data processing methods; we succeeded in identifying odors (gas species) simply by bringing a sensor chip close to samples, leading to a pump-free artificial olfactory sensor. Finally, we show a theoretical model of MSS and discuss the interpretation of sensing signals of MSS on the basis of nanomechanics and physical chemistry.

The “MSS Alliance” was launched in September 2015, as an industry-academia-government joint research framework towards a de facto standard for olfactory sensors/systems based on the MSS technology. The “MSS Forum” was launched on November 1st, 2017, to accelerate practical applications and to meet requests from interested groups in various fields for first-hand experience in the use of MSS olfactory IoT sensing systems developed through the R&D in the MSS Alliance. The seven organizations that make up the MSS Alliance will continue the R&D on constituent technologies while the companies and research institutes who joined the MSS Forum promote experiments to demonstrate the effectiveness of the MSS in various environments, pursuing the establishment of MSS olfactory IoT sensor sensors/systems technologies to achieve a de facto standard.