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Sensors and materials
Scientific Publishing Division
Sensors and materials

Scientific Publishing Division

0914-4935

Sensors and materials/Journal Sensors and materialsISTPSCI
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    SPECIAL ISSUE ON SMART SENSORS FOR CHEMICAL AND AGRICULTURAL APPLICATIONS

    Kazuaki Sawada
    a1-a2页
    查看更多>>摘要：To achieve Society 5.0, it is necessary to deploy a wide variety of sensors in physical spaces. In the future, many sensors will be needed in fields such as medicine, life sciences, and agriculture, but owing to issues such as power consumption and cost, it is not realistic to deploy many individual sensors. I believe that one solution to this problem is edge AI sensing devices. It is essential to integrate a wide variety of sensors into a small chip, detect feature values using CMOS integrated circuit technology, and output meaningful information. Such devices can be realized through the fusion of sensor technology and semiconductor integrated circuit technology. I believe that this will lead to the creation of new services that will solve various social problems.
      原文链接:
    • NETL
    • NSTL

    Enantiomer Identification by Applying Electric Fields of Various Intensities to Microgaps Installed in a Gas Flow Channel

    Manase MizutaniNaho MinowaYong-Joon ChoiKazuhiro Takahashi...
    1299-1310页
    查看更多>>摘要：Enantiomers are molecules whose structures are nonsuperimposable mirror images. Enantiomeric molecules have the same chemical and physical properties but may undergo different biological reactions. Therefore, distinguishing between enantiomers using most equipment is difficult. Thus far, enantiomers can only be identified using expensive analytical methods, such as gas chromatography, and active studies are underway on methods that distinguish between enantiomers using inexpensive gas sensors. Various weak enantiomeric gases are generated from living organisms and pharmaceuticals where asymmetric synthesis is performed. We can obtain detailed chemical information about living organisms and spaces by identifying these gases as different components. In this study, we focused on the charge bias caused by the differing geometric structures of enantiomers. We propose a grid that can apply electric fields of various strengths to a gas flow path. We believe that the electrical force acts on the charge held by the gas molecules, steepening the gas sensor output waveform and increasing the output value. We confirmed that molecules with enantiomeric relationships can be identified using grids. This research is expected to enable gas sensors to detect chemical components in more detailed classifications.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division

    Realizing Short-term Disease Forecasting in Crops via Multimodal Monitoring with Leaf-underside-sensing Agricultural Robot

    Kenji TeradaShigeyoshi OhnoKaori Fujinami
    1311-1331页
    查看更多>>摘要：This study was focused on forecasting diseases in fruit trees five days in advance using supervised machine learning. This involved photographing the undersides of leaves and sensing environmental conditions using agricultural robots. A leaf underside disease classifier that achieved 0.90 accuracy and 0.91 recall based on 330 images collected by the robot-mounted camera was developed. The classifier's results were utilized for binary classifications to predict disease occurrences. This innovative approach aims to enhance disease management in agriculture. Using objective variables in the leaf underside disease classification and feature-increase method, we analyzed disease forecasting methods through the comparison of machine learning models, sensor types, and dataset durations required for training the models. As a result, we clarified the changes in the accuracy of the predicted number of days for each machine learning model. The recall when using the dataset collected by the robot over 16 days was 0.980. Furthermore, we confirmed that the characteristics unique to each farm appeared in the forecast for each sensor used in the observations.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division

    Quantitative Assessment of Chl a and b in Spinach Chl Standard Solution Using a Filter-free Wavelength Sensor

    Ryoma MibuYong-Joon ChoiTomoya IdeYasuyuki Kimura...
    1333-1349页
    查看更多>>摘要：We proposed a quantitative method for assessing chlorophyll (Chl) content and Chl a/b ratio using a filter-free wavelength sensor. Initially, an experiment was conducted to simulate changes in Chl a and b by adjusting the light intensity at wavelengths of 650 and 660 nm. The sensor's output current ratio exhibited a linear relationship with the light intensity, suggesting its potential for measuring Chl. Subsequently, measurements were performed using standard Chl a and b solutions. A strong linear correlation was observed between sensor output and Chl content, independent of changes in Chl a/b ratio. However, no direct correlation was found between sensor output and Chl a/b ratio. This inconsistency was attributed to the varying impact of Chl content changes on the sensor output, depending on the specific Chl a/b ratio. To address this limitation, we proposed a calibration method based on the relationship between Chl content and sensor output. By applying this calibration curve, we successfully reduced the error in Chl a/b ratio measurements. This approach enables the use of filter-free wavelength sensors for the accurate quantification of Chl content and Chl alb ratio, offering a potential solution for on-site monitoring and agricultural applications.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division

    Suppression of Drift in Ion-selective Field Effect Transistor by UV Light Irradiation

    Yasumichi TakaseTakafumi IshigakiShinnosuke NakamuraHideaki Asao...
    1351-1362页
    查看更多>>摘要：Ion-selective field-effect transistors (ISFETs) are a type of potentiometric sensor with a wide range of potential applications. However, the application of ISFETs is hindered by the instability of the threshold voltage (V_T), known as the drift. In this study, we hypothesized that the charge trapping at the interface between the oxide layer and the Si substrate of ISFETs affects the drift, and we examined the effects of the irradiation of UV light on the drift. To investigate the drift more simply, we fabricated a Si wafer sample with a 30 nm Al_2O_3 layer, which is regarded as the sensing layer of an ISFET, and we measured the drift by capacitance-voltage measurements using an electrochemical cell. Results showed that the amount of drift after light irradiation decreased to 6.6% (37 mV/h) relative to the original drift (558 mV/h) in the best case. It was also suggested that the drift is caused by multiple charge trapping mechanisms. These results indicate that charge trapping is a cause of drift, and light irradiation can be used to suppress drift.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division

    Front-light Structure with Excitation Light Polarized for Enhancing Lensless Fluorescence Imaging

    Arphorn PromkingYoshinori SunagaYasumi OhtaRyoma Okada...
    1363-1381页
    查看更多>>摘要：In this study, we introduce a high-performance front-light structure integrated with optical polarization control to improve low-contrast fluorescent imaging in lensless devices. Lensless fluorescence imaging is an advanced technology with the potential to enhance the performance of biological and neurological imaging. However, there are still challenges to achieving high image quality, particularly in low-contrast fluorescent signals due to light scattering and absorption. The performance of a low-fluorescence stripe diffractor, fabricated using Norland Optical Adhesive 63 (NOA 63), was evaluated in comparison to polydimethylsiloxane (PDMS) material as a light guide. The diffractor is designed to operate with a hybrid emission filter on the image sensor. As a result, by coupling a 450 nm laser with either P- or S-polarization, it was shown that NOA 63 is notable as a diffractor material. Notably, S-polarized light showed a great excitation intensity and an enhanced contrast in fluorescent bead imaging compared with P-polarized light. Furthermore, the system was validated for biological applications by successfully detecting fluorescent bead emission in agarose-embedded samples of various thicknesses, simulating brain tissue. These results emphasize the system's ability to capture low-intensity fluorescence signals from deep layers of biological tissue.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division

    Syngas Formation by Microwave-induced Co-Mo and Ni-Mo Catalysts

    Chih Ju G. JouChien Li Lee
    1527-1535页
    查看更多>>摘要：In this study, the microwave-induced Co-Mo and Ni-Mo catalysts were combined with a high-dielectric-constant medium to absorb microwave energy and convert it into the heat energy required for syngas production. The microwave conditions were a microwave power of 450 W and a total microwave time of 210 min with the volume ratios CH_4/air =1:2 (partial oxidation) and CH_4/CO_2 = 2:1 (dry reforming reaction). The results showed that the average yields of H_2 and CO were 43 and 35.7% in the partial oxidation reaction with Ni-Mo as catalyst, whereas those in the dry reforming reaction were 44.4 and 24.9%, respectively. On the other hand, with Co-Mo as the catalyst, the average yields of H_2 and CO were 50.7 and 35.9% in the partial oxidation reaction, whereas those in the dry reforming reaction were 62.6 and 40.6%, respectively. Owing to the high activity of the Ni-Mo catalyst, it is easier to shield the metal coated on the surface by coke deposition. As the reaction time proceeds, the activity of the Ni-Mo catalyst decreases, and the syngas yield is reduced. Therefore, it is feasible and innovative to combine microwave-induced Ni-Mo and Co-Mo catalysts with a high-dielectric-constant medium to absorb and convert microwave energy into heat energy to produce syngas.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division

    Measurement Circuit Design of 3-in-1 Microsensor Embedded in Proton Exchange Membrane Water Electrolyzer

    Chi-Yuan LeeZhi-Yu HuangJia-Yu HsuTing-Fu Kuo...
    1537-1550页
    查看更多>>摘要：The proton exchange membrane water electrolyzer (PEMWE) has the advantages of simplicity, small size, high current density, and high operating temperature, but it is easy to cause corrosion and oxidation to the gas diffusion layer or electrode at the oxygen end during electrolysis, which will accelerate the degradation of its performance. Therefore, a flexible 3-in-1 microsensor (temperature, voltage, and current) was developed using MEMS technology and embedded inside the PEMWE used in this study, and the circuit was designed and the data was observed in real time by Arduino Mega 2560. When the PEMWE is running, a flexible 3-in-1 microsensor can predict the performance in advance and obtain valuable information about the aging or failure of the PEMWE, so that it can be warned and adjusted in time.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division

    Improved Mango Disease Detection Model for Energy-efficient Edge Computing Device

    Wen-Tsai SungIndra Griha Tofik IsaSung-Jung Hsiao
    1551-1568页
    查看更多>>摘要：Mango is a fruit that has high economic value for several countries, so it is widely cultivated through technological engineering, including the implementation of artificial intelligence through vision sensing based on object detection methods. In this study, we proposed a detection model by integrating a You-Only-Look-Once version 7 Tiny (YOLOv7-Tiny) detection model and U-Net segmentation to detect plant growth through mango leaf diseases. The dataset development was carried out through image collection from several resources and image augmentation, which resulted in a total of 13004 images consisting of eight classes, namely, anthracnose, bacterial canker, cutting weevil, die back, gall midge, sooty mold, powdery mildew, and normal. The training, testing, and validation data were set to 70, 20, and 10%, respectively. The comparative experiment involved other models, namely, YOLOv4-Tiny, YOLOv5n, YOLOv7-Tiny, and YOLOv8n. The experimental results showed that the proposed model has outstanding performance compared with the other models with a mean average precision of 90.22%, while precision, recall, and F1-score have the percentages of 88.42, 87.93, and 88.17%, respectively. In practical applications, the proposed model has significant results in detecting mango leaf diseases. Moreover, the proposed model has good performance in terms of energy efficiency, which is represented by the model size and inference time generated by the model.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division

    A Mouthguard-type Biosensor for Direct Measurement of Glucose Intake in Drinks

    Kenta IchikawaKenta IitaniYumin ZhaoKoji Toma...
    1569-1578页
    查看更多>>摘要：Glucose in drinks is one of the key factors in the management and prevention of diabetes. Although several systems have been developed to monitor blood glucose levels as an indicator of diabetes, information on the actual intake of nutrients and their amounts is more effective for improving dietary habits. In this study, to evaluate the actual amount of glucose intake, we proposed a mouthguard-type sensor with an enzymatic biosensor for the direct measurement of the glucose concentration of ingested drinks. The fabricated biosensor was capable of quantifying glucose concentrations in the range of 1 μM-1 mM and showed measurement results equivalent to those of glucose measurement kits for some commercial drinks. The mouthguard-type sensor also showed quantification characteristics equivalent to the biosensor in wired measurements. In addition, wireless measurements with a mouthguard-type sensor were also demonstrated using a Bluetooth Low Energy potentiostat. These results suggest the potential application of real-time glucose intake measurement with the proposed mouthguard-type sensor.
      原文链接:
    • NETL
    • NSTL
    • Myu, Scientific Publishing Division