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14 pages, 1807 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Batch-to-Batch Variation in Laser-Inscribed Graphene (LIG) Electrodes for Electrochemical Sensing

by Yifan Tang, Geisianny A. Moreira, Diana Vanegas, Shoumen P. A. Datta and Eric S. McLamore

Micromachines 2024, 15(7), 874; https://doi.org/10.3390/mi15070874 - 30 Jun 2024

Viewed by 907

Abstract

Laser-inscribed graphene (LIG) is an emerging material for micro-electronic applications and is being used to develop supercapacitors, soft actuators, triboelectric generators, and sensors. The fabrication technique is simple, yet the batch-to-batch variation of LIG quality is not well documented in the literature. In [...] Read more.

Laser-inscribed graphene (LIG) is an emerging material for micro-electronic applications and is being used to develop supercapacitors, soft actuators, triboelectric generators, and sensors. The fabrication technique is simple, yet the batch-to-batch variation of LIG quality is not well documented in the literature. In this study, we conduct experiments to characterize batch-to-batch variation in the manufacturing of LIG electrodes for applications in electrochemical sensing. Numerous batches of 36 LIG electrodes were synthesized using a CO₂ laser system on polyimide film. The LIG material was characterized using goniometry, stereomicroscopy, open circuit potentiometry, and cyclic voltammetry. Hydrophobicity and electrochemical screening (cyclic voltammetry) indicate that LIG electrode batch-to-batch variation is less than 5% when using a commercial reference and counter electrode. Metallization of LIG led to a significant increase in peak current and specific capacitance (area between anodic/cathodic curve). However, batch-to-batch variation increased to approximately 30%. Two different platinum electrodeposition techniques were studied, including galvanostatic and frequency-modulated electrodeposition. The study shows that formation of metallized LIG electrodes with high specific capacitance and peak current may come at the expense of high batch variability. This design tradeoff has not been discussed in the literature and is an important consideration if scaling sensor designs for mass use is desired. This study provides important insight into the variation of LIG material properties for scalable development of LIG sensors. Additional studies are needed to understand the underlying mechanism(s) of this variability so that strategies to improve the repeatability may be developed for improving quality control. The dataset from this study is available via an open access repository. Full article

(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)

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11 pages, 7984 KiB

Open AccessArticle

Non-Destructive Sensor for Glucose Solution Concentration Detection Using Electromagnetic Technology

by Shasha Yang, Shiwen Gao, Yi Zhuang, Wence Hu, Junyi Zhao and Zhenxiang Yi

Micromachines 2024, 15(6), 758; https://doi.org/10.3390/mi15060758 - 5 Jun 2024

Viewed by 659

Abstract

In this paper, a sensor using a complementary split ring resonator (CSRR) is proposed for non-destructive testing of blood glucose. By depicting the complementary split ring structure on the ground, the electromagnetic field strength between the split rings can be enhanced effectively. The [...] Read more.

In this paper, a sensor using a complementary split ring resonator (CSRR) is proposed for non-destructive testing of blood glucose. By depicting the complementary split ring structure on the ground, the electromagnetic field strength between the split rings can be enhanced effectively. The structure size of the sensor by CSRR is determined by simulation, so that the insertion loss curve of the device has a resonance point at the frequency of 3.419 GHz. With a special holder created by three-dimensional (3D) printing technology, the test platform was established when the concentration of the solution varied from 0 mg/mL to 20 mg/mL. The experimental results indicate that there is an obvious linear relationship between the insertion loss S₂₁ and the glucose concentration at the resonant frequency. Similarly, the measured real part and imaginary part of the S₂₁ both vary with glucose concentration linearly. Based on the above experimental results, the feasibility of the sensor using a CSRR proposed in this paper for non-destructive detection of blood glucose is preliminarily verified. Full article

(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)

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12 pages, 5208 KiB

Open AccessArticle

A Modulation Method for Tunnel Magnetoresistance Current Sensors Noise Suppression

by Shuaipeng Wang, Haichao Huang, Ying Yang, Yanning Chen, Zhen Fu, Zhenhu Jin, Zhenyu Shi, Xingyin Xiong, Xudong Zou and Jiamin Chen

Micromachines 2024, 15(3), 360; https://doi.org/10.3390/mi15030360 - 1 Mar 2024

Cited by 1 | Viewed by 1218

Abstract

To mitigate the impact of low-frequency noise from the tunnel magnetoresistance (TMR) current sensor and ambient stray magnetic fields on weak current detection accuracy, we propose a high-resolution modulation-demodulation test method. This method modulates and demodulates the measurement signal, shifting low-frequency noise to [...] Read more.

To mitigate the impact of low-frequency noise from the tunnel magnetoresistance (TMR) current sensor and ambient stray magnetic fields on weak current detection accuracy, we propose a high-resolution modulation-demodulation test method. This method modulates and demodulates the measurement signal, shifting low-frequency noise to the high-frequency band for effective filtering, thereby isolating the target signal from the noise. In this study, we developed a Simulink model for the TMR current sensor modulation-demodulation test method. Practical time-domain and frequency-domain tests of the developed high-resolution modulation-demodulation method revealed that the TMR current sensor exhibits a nonlinearity as low as 0.045%, an enhanced signal-to-noise ratio (SNR) of 77 dB, and a heightened resolution of 100 nA. The findings indicate that this modulation-demodulation test method effectively reduces the impact of low-frequency noise on TMR current sensors and can be extended to other types of resistive devices. Full article

(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)

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20 pages, 13086 KiB

Open AccessArticle

Comparison and Verification of Three Algorithms for Accuracy Improvement of Quartz Resonant Pressure Sensors

by Bin Yao, Yanbo Xu, Junming Jing, Wenjun Zhang, Yuzhen Guo, Zengxing Zhang, Shiqiang Zhang, Jianwei Liu and Chenyang Xue

Micromachines 2024, 15(1), 23; https://doi.org/10.3390/mi15010023 - 22 Dec 2023

Viewed by 1123

Abstract

Pressure measurement is of great importance due to its wide range of applications in many fields. AT-cut quartz, with its exceptional precision and durability, stands out as an excellent pressure transducer due to its superior accuracy and stable performance over time. However, its [...] Read more.

Pressure measurement is of great importance due to its wide range of applications in many fields. AT-cut quartz, with its exceptional precision and durability, stands out as an excellent pressure transducer due to its superior accuracy and stable performance over time. However, its intrinsic temperature dependence significantly hinders its potential application in varying temperature environments. Herein, three different learning algorithms (i.e., multivariate polynomial regression, multilayer perceptron networks, and support vector regression) are elaborated in detail and applied to establish the prediction models for compensating the temperature effect of the resonant pressure sensor, respectively. The AC-cut quartz, which is sensitive to temperature variations, is paired with the AT-cut quartz, providing the essential temperature information. The output frequencies derived from the AT-cut and AC-cut quartzes are selected as input data for these learning algorithms. Through experimental validation, all three methods are effective, and a remarkable improvement in accuracy can be achieved. Among the three methods, the MPR model has exceptionally high accuracy in predicting pressure. The calculated residual error over the temperature range of −10–40 °C is less than 0.008% of 40 MPa full scale (FS). An intelligent automatic compensation and real-time processing system for the resonant pressure sensor is developed as well, which may contribute to improving the efficiency in online calibration and large-scale industrialization. This paper paves a promising way for the temperature compensation of resonant pressure sensors. Full article

(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)

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11 pages, 4874 KiB

Open AccessArticle

MEMS Fluxgate Sensor Based on Liquid Casting

by Ying Yang, Wei Xu, Guangyuan Chen, Zhenhu Jin, Dandan Wang, Zhihong Mai, Guozhong Xing and Jiamin Chen

Micromachines 2023, 14(12), 2159; https://doi.org/10.3390/mi14122159 - 26 Nov 2023

Viewed by 1198

Abstract

Compared with electroplating, liquid casting enables the rapid formation of a three-dimensional solenoid coil with a narrower line width and greater thickness, which proves advantageous in enhancing the comprehensive performance of the micro-electromechanical system (MEMS) fluxgate sensor. For this reason, a MEMS fluxgate [...] Read more.

Compared with electroplating, liquid casting enables the rapid formation of a three-dimensional solenoid coil with a narrower line width and greater thickness, which proves advantageous in enhancing the comprehensive performance of the micro-electromechanical system (MEMS) fluxgate sensor. For this reason, a MEMS fluxgate sensor based on liquid casting with a closed-loop Fe-based amorphous alloy core is proposed. Based on the process parameters of liquid casting, the structure of the MEMS fluxgate sensor was designed. Utilizing MagNet to build the simulation model, the optimal excitation conditions and sensitivity were obtained. According to the simulation model, a highly sensitive MEMS fluxgate sensor based on liquid casting was fabricated. The resulting sensor exhibits a sensitivity of 2847 V/T, a noise of 306 pT/√Hz@1 Hz, a bandwidth of DC-10.5 kHz, and a power consumption of 43.9 mW, which shows high sensitivity and low power consumption compared with other MEMS fluxgates in similar size. Full article

(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)

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14 pages, 7535 KiB

Open AccessArticle

On-Demand Dynamic Terahertz Polarization Manipulation Based on Pneumatically Actuated Metamaterial

by Yongchao Zou, Yan Wang, Yangjian Zeng, Pan Xu, Zhengliang Hu and Hongbin Yu

Micromachines 2023, 14(11), 2094; https://doi.org/10.3390/mi14112094 - 12 Nov 2023

Viewed by 1248

Abstract

In this paper, a new tuning strategy is proposed by incorporating a pneumatically actuated metamaterial to achieve on-demand polarization manipulation at THz frequencies. Through controlling the actuation pressure, the device function can be flexibly switched among three types of polarization conversion capabilities within [...] Read more.

In this paper, a new tuning strategy is proposed by incorporating a pneumatically actuated metamaterial to achieve on-demand polarization manipulation at THz frequencies. Through controlling the actuation pressure, the device function can be flexibly switched among three types of polarization conversion capabilities within the same operation frequency band, from 1.3 THz to 1.5 THz, in which the mutual conversion between linear polarization and circular polarization, such as a quarter-wave plate, and handedness inversion between circular polarizations as a helicity inverter as well as a helicity keeper, have been successfully achieved between the incidence and reflection. Moreover, the intrinsic tuning mechanism for the polarization manipulation is also discussed. Full article

(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)

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10 pages, 6138 KiB

Open AccessArticle

Micro 4D Imaging Sensor Using Snapshot Narrowband Imaging Method

by Wei Jiang, Dingrong Yi, Caihong Huang, Qing Yu and Linghua Kong

Micromachines 2023, 14(9), 1689; https://doi.org/10.3390/mi14091689 - 29 Aug 2023

Cited by 1 | Viewed by 2046

Abstract

The spectral and depth (SAD) imaging method plays an important role in the field of computer vision. However, accurate depth estimation and spectral image capture from a single image without increasing the volume of the imaging sensor is still an unresolved problem. Our [...] Read more.

The spectral and depth (SAD) imaging method plays an important role in the field of computer vision. However, accurate depth estimation and spectral image capture from a single image without increasing the volume of the imaging sensor is still an unresolved problem. Our research finds that a snapshot narrow band imaging (SNBI) method can discern wavelength-dependent spectral aberration and simultaneously capture spectral-aberration defocused images for quantitative depth estimation. First, a micro 4D imaging (M4DI) sensor is proposed by integrating a mono-chromatic imaging sensor with a miniaturized narrow-band microarrayed spectral filter mosaic. The appearance and volume of the M4DI sensor are the same as the integrated mono-chromatic imaging sensor. A simple remapping algorithm was developed to separate the raw image into four narrow spectral band images. Then, a depth estimation algorithm is developed to generate 3D data with a dense depth map at every exposure of the M4DI sensor. Compared with existing SAD imaging method, the M4DI sensor has the advantages of simple implementation, low computational burden, and low cost. A proof-of-principle M4DI sensor was applied to sense the depth of objects and to track a tiny targets trajectory. The relative error in the three-dimensional positioning is less than 7% for objects within 1.1 to 2.8 m. Full article

(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)

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Review

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20 pages, 2487 KiB

Open AccessReview

Electrochemical Assays for the Determination of Antidiabetic Drugs—A Review

by Katarzyna Fendrych, Anna Górska-Ratusznik and Joanna Smajdor

Micromachines 2024, 15(1), 10; https://doi.org/10.3390/mi15010010 - 20 Dec 2023

Cited by 1 | Viewed by 1077

Abstract

This article presents the current state of knowledge regarding electrochemical methods for determining the active substances within drugs that are used in the treatment of type 1 and type 2 diabetes. Electrochemical methods of analysis, due to their sensitivity and easiness, are a [...] Read more.

This article presents the current state of knowledge regarding electrochemical methods for determining the active substances within drugs that are used in the treatment of type 1 and type 2 diabetes. Electrochemical methods of analysis, due to their sensitivity and easiness, are a great alternative to other, usually more expensive analytical assays. The determination of active substances mentioned in this review is based on oxidation or reduction processes on the surface of the working electrode. A wide variety of working electrodes, often modified with materials such as nanoparticles or conducting polymers, have been used for the highly sensitive analysis of antidiabetic drugs. The presented assays allow us to determine the compounds of interest in various samples, such as pharmaceutical products or different human bodily fluids. Full article

(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)

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