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This document provides a design description of a data acquisition device that allows an alert to be issued to suggest to the driver to take a break after having subjected his body to a certain amount of acceleration and pressure changes after driving on a road with too many curves. The tests were carried out using sensors based on microelectromechanical systems. The system was strategically installed at specific points on the body of the driver and car. Several electronic arrays were carried out, like the design of a printed circuit board. The establishment of an inter-integrated circuit communication and its multiplexing to work with several devices with the same address simultaneously. Finally, in this context, the document also presents the critical velocity for each curve in the Hakone roadway, which was obtained by using a mathematical model and contrasted with data acquisition values for acceleration. The risk of skidding on a curve increases when the driver does not reduce driving velocity; only a slight variance in acceleration or environmental conditions is enough. The value of acceleration was acquired for the analysis of each curve; there is a greater possibility of skidding in curves 2 and 4 because their radius is smaller and the critical speed is approximately 60 km/h, which is very close to the driving speed. On the other hand, the deceleration value of −0.65 G read on the head accelerometer can increase fatigue symptoms such as blurry vision or dizziness. [ABSTRACT FROM AUTHOR]

This paper describes a wireless and battery‐free soil pH sensor made entirely of degradable materials. Soil pH monitoring is significant for precision agriculture and environmental conservation because soil health can be estimated by measuring soil pH. Soil pH can be measured by collecting soil samples and analyzing them in a laboratory environment or by inserting an electrode‐type sensor into the soil and measuring soil pH on site. However, neither method is suitable for wide‐area soil pH sensing for precision agriculture or environmental conservation. Herein, a fully biodegradable wireless pH sensor is presented that can be dispersed to outdoor environment to detect soil acidity. The sensor is operated wirelessly through split‐ring resonators (SRRs) that consist of patterned octacalcium phosphate (OCP)‐coated magnesium (Mg) on a poly‐lactic acid (PLA) sheet. At acidic soil pH, the degradation of each SRR results in a change in the electromagnetic response of the sensor. The operation of the sensor in six different types of acidic soils is demonstrated to distinguish the acidic soil wirelessly. It is expected that the biodegradable sensor can be applied to low‐cost, easy‐to‐use, and environmentally friendly monitoring of soil pH. [ABSTRACT FROM AUTHOR]

Controlling polarization using metamaterials has been one of the research areas that attract immense attention. In particular, the symmetry of the structure plays an important role in controlling polarization-sensitive optical phenomena. Circular polarization control, which is used for important applications such as circular dichroism spectroscopy, requires designing the symmetry of a metamaterial with circular polarization eigenstates. In the linear response, a giant optical activity was observed in chiral metamaterials. It is possible to actively tune the magnitude and sign of polarization by external stimuli or deforming the chiral metamaterial. Furthermore, in the nonlinear optical response, the metamaterial having the rotational symmetry enables wavelength conversion of circularly polarized light and also controls the phase thereof. This article provides an overview of these previous achievements on the metamaterials for controlling circular polarization with isotropic linear response. The article also discusses the prospects of these technologies that will enable polarization control, not only in the visible region but also in the long-wavelength (terahertz) and extremely short-wavelength (vacuum ultraviolet and extreme ultraviolet) regions in combination with the two advanced technologies: high-order harmonic generation and microelectromechanical systems. [ABSTRACT FROM AUTHOR]