センサ・マイクロマシン部門誌（論文誌E）では，平成25年度より，総合研究会で講演された論文に関する特集号を企画しており，今回は本誌2023年5月号にて刊行されることになりました。掲載されている論文は「令和4年度センサ・マイクロマシン部門総合研究会」（2022（令和4）年

A polyclonal antibody against the analog of piperine, which is a typical pungent taste substance, was produced, and its binding ability to piperine was evaluated using a surface plasmon resonance sensor. The antibody was labeled with glucose oxidase (GOx), and the hydrogen ions produced by the enzymatic reaction were measured at a lipid polymer membrane electrode for sourness in a taste sensor. The results showed that piperine could be detected by that polyclonal antibody; the response of the sourness sensor increased in dependence on the GOx-labeled antibody concentration when the GOx of GOx-labeled antibody was reacted with glucose. Thus, it was shown that uncharged pungent compounds can be converted into hydrogen ions. Pungent taste can be measured by the taste sensor using GOx-labeled antibodies, and GOx-labeled antibodies can be used as a pretreatment.

Oxygen and nutrient supply provided via the vascular system is essential for organ development and tissue metabolism. Recent advances in stem cell technologies have led to the development of complex 3D tissue culture systems. However, direct supply of nutrients and oxygen by simple diffusion fails to reach inner areas resulting in impaired maturity of these complex tissues over time. In an attempt to alleviate this problem, 3D tissues are integrated with vascular networks (VNs) on a chip to ensure appropriate oxygen and nutrient supply. Such an in vitro vascular system must maintain a stable, robust, and perfusable network without degradation during entire culture period that may easily exceed several weeks. Current protocols for generation of VNs provide no information on the changes in these parameters in the long term. Here, using human umbilical vein endothelial cells, we generated a vascular network on a microfluidic chip and evaluated its morphology and function for 35 days. We demonstrate network stability, preservation of lumen structure and robust perfusability with negligible increase in permeability over time.

In agricultural field, compact sensors that can measure both water content and electric conductivity are needed. Focusing on the fact that water content and conductivity depend on soil impedance, our group has been developing a new compact and noise-resistant driving circuit that measured soil impedance by detecting transient characteristics of the voltage obtained by injecting current through the soil and converting it to frequency information. In order to realize agricultural field measurements with sensors using this new driving circuit, it had been necessary to miniaturize the part that detected the output from the driving circuit, but it hadn't been achieved in our previous work. In this research, a microcomputer-based frequency counter was developed to downsize the system for on-site measurement. In general, there are two methods of frequency measurement: direct counting and reciprocal. The direct-counting method is suited for high-frequency measurements, while the reciprocal method is suited for low-frequency measurements. The developed frequency counter could measure with an error of 0.005% over the assumed frequency range by switching between those two measurement methods according to the measured frequency. Using this driving circuit and frequency counter, we measured the model soil and succeeded in capturing changes in water content as changes in impedance.