センサ・マイクロマシン部門誌（論文誌E）では，2014年から英語の論文・レターのみを集めた「英文特集号」を発行しております。2014年～2016年の3月号，2017年～2020年の1月号，そして2021年1月号に引き続き，本年1月号にも特集号を発行することになりました。

A wireless stent flow sensor system was developed to evaluate the changes in breathing characteristics in the airways of experimental animals caused due to drug administration under free movement conditions for drug development. The system was composed of a stent flow sensor, a signal conditioning module, and a PC module. To develop the stent flow sensor, a tube flow sensor and a stent structure were separately fabricated, and they were interlocked at the connection area formed on both elements. The analog sensor outputs were converted into digital outputs with a sampling frequency of 1.0 kHz in a signal conditioning module and transmitted to a PC module through Bluetooth Low Energy 5.0 operated at 2.4 GHz, as the wireless communication. The stent flow sensor and the signal conditioning module were operated using a 165-mAh battery. A simulation experiment was conducted using a plush doll after obtaining calibration curves. A transparent tube was used as the airway and it was placed inside the doll, and an artificial ventilator designed for a small experimental animal was connected to the tube. The stent flow sensor fixed inside the tube was connected to the airway tube, and the signal conditioning module was placed on the back of the neck of the doll. The stent flow sensor output was successfully transmitted to the PC module through Bluetooth. It was demonstrated that the system developed in this study can measure the breathing airflow with a tidal volume accuracy of less than 3.7%.

We have realized an infrared (IR) photodiode with silicon for the future beyond-VLSI photonics. Colloidal quantum dot (CQD) integration with Si is a simple process. We previously reported a PbS CQD/ZnO/Si hybrid IR photodiode. The device had an absorption peak at 1230 nm. To improve the quantum efficiency, we investigated the dose levels of Si substrates and improved the external quantum efficiency (EQE) by using a structural approach, such as using a higher doping level of Si. We achieved a 1230 nm absorption peak with an ITO/Au/PbS-EDT/PbS-I CQDs/ZnO/Si hybrid IR photodiode with an EQE close to 7%, at a reverse bias of -0.5 V.

The effects of metal-nitrate receptors on the NO_X sensing properties of an impedancemetric solid-state sensor were investigated using a solid Li_1.5Al_0.5Ti_1.5(PO₄)₃ (LATP) electrolyte disc as an impedance transducer and various metal nitrates as receptors. Although most of the metal nitrates could not act as sensor receptors, an LATP-based sensor with KNO₃ exhibited high sensitivity to NO and NO₂ at 300 °C.

To fabricate a nanohole array chip, a mask in nanosphere lithography was fabricated by drag-coating convective self-assembly using two glass slides. The relationship between the volume fraction of 500-nm-diameter polystyrene (PS) particles and the deposition rate under our experimental conditions was determined. Masks with a monolayer of PS particles were deposited on glass slides. Plasma etching of the PS particles was carried out to reduce their diameter. Au was sputtered over the mask, and the mask was then removed. Finally, a nanohole array was obtained using this simple procedure.