Rapid Fabrication of Large-Grain Opal Films and Photonic Crystal Hydrogel Sensors by a Filter Paper-Enhanced Evaporation Chip.

Developing a rapid fabrication method for crack-free opal films is a significant challenge with broad applications. We developed a microfluidic platform known as the "filter paper-enhanced evaporation microfluidic chip" (FPEE-chip) for the fabrication of photonic crystal and inverse opal hydrogel (IOPH) films. The chip featured a thin channel formed by bonding double-sided adhesive poly(ethylene terephthalate) with a polymethyl methacrylate cover and a glass substrate. This channel was then filled with nanosphere colloids. The water was guided to evaporate rapidly at the surface of the filter paper, allowing the nanospheres to self-assemble and accumulate within the channel under capillary forces. Experimental results confirmed that the self-assembly method based on the FPEE-chip was a rapid platform for producing high-quality opal, with centimeter-sized opal films achievable in less than an hour. Furthermore, the filter paper altered the stress release mechanism of the opal films during drying, resulting in fewer cracks. This platform was proven capable of producing large-grain, crack-free opal films of up to 30 mm2 in size. We also fabricated crack-free IOPH pH sensors that exhibited color and size responsiveness to pH changes. The coefficient of variation of the gray color distribution for crack-free IOPH ranged from 0.03 to 0.07, which was lower than that of cracked IOPH (ranging from 0.07 to 0.14). Additionally, the grayscale peak value in 1 mm2 of the crack-free IOPH was more than twice that of the cracked IOPH at the same pH. The FPEE-chip demonstrated potential as a candidate for developing vision sensors.

SE-VisionTransformer: Hybrid Network for Diagnosing Sugarcane Leaf Diseases Based on Attention Mechanism.

Sugarcane is an important raw material for sugar and chemical production. However, in recent years, various sugarcane diseases have emerged, severely impacting the national economy. To address the issue of identifying diseases in sugarcane leaf sections, this paper proposes the SE-VIT hybrid network. Unlike traditional methods that directly use models for classification, this paper compares threshold, K-means, and support vector machine (SVM) algorithms for extracting leaf lesions from images. Due to SVM's ability to accurately segment these lesions, it is ultimately selected for the task. The paper introduces the SE attention module into ResNet-18 (CNN), enhancing the learning of inter-channel weights. After the pooling layer, multi-head self-attention (MHSA) is incorporated. Finally, with the inclusion of 2D relative positional encoding, the accuracy is improved by 5.1%, precision by 3.23%, and recall by 5.17%. The SE-VIT hybrid network model achieves an accuracy of 97.26% on the PlantVillage dataset. Additionally, when compared to four existing classical neural network models, SE-VIT demonstrates significantly higher accuracy and precision, reaching 89.57% accuracy. Therefore, the method proposed in this paper can provide technical support for intelligent management of sugarcane plantations and offer insights for addressing plant diseases with limited datasets.

A compact microfluidic laser-induced fluorescence immunoassay system using avalanche photodiode for rapid detection of alpha-fetoprotein.

Alpha-fetoprotein (AFP), commonly employed for early diagnosis of liver cancer, serves as a biomarker for cancer screening and diagnosis. Combining the high sensitivity and specificity of fluorescence immunoassay (FIA), developing a low-cost and efficient immunoassay system for AFP detection holds significant importance in disease diagnosis. In this work, we developed a miniaturized oblique laser-induced fluorescence (LIF) immunoassay system, coupled with a microfluidic PMMA/paper hybrid chip, for rapid detection of AFP. The system employed an avalanche photodiode (APD) as the detector, and implemented multi-level filtering in the excitation light channel using the dichroic mirror and optical trap. At first, we employed the Savitzky-Golay filter and baseline off-set elimination methods to denoise and normalize the original data. Then the cutoff frequency of the low-pass filter and the reverse voltage of the APD were optimized to enhance the detection sensitivity of the system. Furthermore, the effect of laser power on the fluorescence excitation efficiency was investigated, and the sampling time during the scanning process was optimized. Finally, a four-parameter logistic (4PL) model was utilized to establish the concentration-response equation for AFP. The system was capable of detecting concentrations of AFP standard solution within the range of 1-500 ng/mL, with a detection limit of 0.8 ng/mL. The entire immunoassay process could be completed within 15 min. It has an excellent potential for applications in low-cost portable diagnostic instruments for the rapid detection of biomarkers.

Three-dimensional array of microbubbles sonoporation of cells in microfluidics.

Sonoporation is a popular membrane disruption technique widely applicable in various fields, including cell therapy, drug delivery, and biomanufacturing. In recent years, there has been significant progress in achieving controlled, high-viability, and high-efficiency cell sonoporation in microfluidics. If the microchannels are too small, especially when scaled down to the cellular level, it still remains a challenge to overcome microchannel clogging, and low throughput. Here, we presented a microfluidic device capable of modulating membrane permeability through oscillating three-dimensional array of microbubbles. Simulations were performed to analyze the effective range of action of the oscillating microbubbles to obtain the optimal microchannel size. Utilizing a high-precision light curing 3D printer to fabricate uniformly sized microstructures in a one-step on both the side walls and the top surface for the generation of microbubbles. These microbubbles oscillated with nearly identical amplitudes and frequencies, ensuring efficient and stable sonoporation within the system. Cells were captured and trapped on the bubble surface by the acoustic streaming and secondary acoustic radiation forces induced by the oscillating microbubbles. At a driving voltage of 30 Vpp, the sonoporation efficiency of cells reached 93.9% ± 2.4%.

A centrifugal-driven spiral microchannel microfiltration chip for emulsion and deformable particle sorting.

Droplet sorting and enrichment, as a prominent field within microfluidic technology, represent a pivotal stage in the manipulation of droplets and particles. In recent times, droplet sorting methods based on lab-on-disk (LOD) have garnered significant interest among researchers for their inherent merits, including high throughput, ease of operation, seamless device integration, and independence from supplementary driving forces. This study introduces a centrifugal force-driven microfluidic chip comprising spiral microchannels. The chip incorporates microhole arrays along the sidewall of the spiral channels, enabling size-based sorting and enrichment of microdroplets under the influence of multiple forces. Firstly, a comparative analysis was performed to assess the influence of the separation port structure and rotational speed on efficiency, and a mechanical modeling approach was employed to conduct kinetic analyses of droplet behavior during instantaneous separation. Those findings demonstrated a good agreement with the experimental results at ω < 100 rpm. Subsequently, sorting experiments on homogeneous droplets indicated that repetitive sorting could increase the recovery ratios, RT(α), of high-concentration droplets (20.7%) from 35.3% to over 80%. We also conducted a sorting experiment on three-component homogeneous-phase emulsions using a serially connected chip array, and the sorting throughput was 0.58 mL min-1. As a result, the RT(α) for 60 and 160 µm droplets were 99.4% and 88.9%, respectively. Lastly, we conducted elution experiments and dual-sample sorting on a single chip, and the fluorescence results demonstrated that this study provided an efficient and non-cross-contaminating sorting method for non-homogenous phase multi-sample microreactor units.

Capillary Force-Driven Quantitative Plasma Separation Method for Application of Whole Blood Detection Microfluidic Chip.

Separating plasma or serum from blood is essential for precise testing. However, extracting precise plasma quantities outside the laboratory poses challenges. A recent study has introduced a capillary force-driven membrane filtration technique to accurately separate small plasma volumes. This method efficiently isolates 100-200 µL of pure human whole blood with a 48% hematocrit, resulting in 5-30 µL of plasma with less than a 10% margin of error. The entire process is completed within 20 min, offering a simple and cost-effective approach to blood separation. This study has successfully addressed the bottleneck in self-service POCT, ensuring testing accuracy. This innovative method shows promise for clinical diagnostics and point-of-care testing.

Sugarcane nitrogen nutrition estimation with digital images and machine learning methods.

The color and texture characteristics of crops can reflect their nitrogen (N) nutrient status and help optimize N fertilizer management. This study conducted a one-year field experiment to collect sugarcane leaf images at tillering and elongation stages using a commercial digital camera and extract leaf image color feature (CF) and texture feature (TF) parameters using digital image processing techniques. By analyzing the correlation between leaf N content and feature parameters, feature dimensionality reduction was performed using principal component analysis (PCA), and three regression methods (multiple linear regression; MLR, random forest regression; RF, stacking fusion model; SFM) were used to construct N content estimation models based on different image feature parameters. All models were built using five-fold cross-validation and grid search to verify the model performance and stability. The results showed that the models based on color-texture integrated principal component features (C-T-PCA) outperformed the single-feature models based on CF or TF. Among them, SFM had the highest accuracy for the validation dataset with the model coefficient of determination (R2) of 0.9264 for the tillering stage and 0.9111 for the elongation stage, with the maximum improvement of 9.85% and 8.91%, respectively, compared with the other tested models. In conclusion, the SFM framework based on C-T-PCA combines the advantages of multiple models to enhance the model performance while enhancing the anti-interference and generalization capabilities. Combining digital image processing techniques and machine learning facilitates fast and nondestructive estimation of crop N-substance nutrition.

A pH-mediated field amplification sample stacking technique based on portable microchip electrophoresis heavy metal ion detection system.

We built a portable microchip electrophoresis heavy metal ion detection system and proposed a pH-mediated field amplified sample stacking (pH-mediated FASS) online preconcentration method. The pH-mediated FASS focuses and stacks heavy metal cations by controlling electrophoretic mobilities with a pH change between the analyte and the background electrolyte (BGE) in solution to improve the detection sensitivity of the system. We optimized and adjusted sample matrix solution (SMS) ratios and pH to create concentration and pH gradients for SMS and BGE. Furthermore, we optimize the microchannel width to improve the preconcentration effect further. The system and method analyzed soil leachates polluted with heavy metals and separated Pb2+ and Cd2+ within 90 s, obtaining their levels at 58.01 mg/L and 4.91 mg/L with sensitivity enhancement factors (SEF) of 26.40 and 43.73. Compared with inductively coupled plasma atomic emission spectrometry (ICP-AES), the detection error of the system was less than 8.80%.

A Microfluidic System of Gene Transfer by Ultrasound.

Ultrasonic gene transfer has advantages beyond other cell transfer techniques because ultrasound does not directly act on cells, but rather pushes the gene fragments around the cells into cells through an acoustic hole effect. Most examples reported were carried out in macro volumes with conventional ultrasonic equipment. In the present study, a MEMS focused ultrasonic transducer based on piezoelectric thin film with flexible substrate was integrated with microchannels to form a microfluidic system of gene transfer. The core part of the system is a bowl-shaped curved piezoelectric film structure that functions to focus ultrasonic waves automatically. Therefore, the low input voltage and power can obtain the sound pressure exceeding the cavitation threshold in the local area of the microchannel in order to reduce the damage to cells. The feasibility of the system is demonstrated by finite element simulation and an integrated system of MEMS ultrasonic devices and microchannels are developed to successfully carry out the ultrasonic gene transfection experiments for HeLa cells. The results show that having more ultrasonic transducers leads a higher transfection rate. The system is of great significance to the development of single-cell biochip platforms for early cancer diagnosis and assessment of cancer treatment.

Ultrastructure of Apocolpodidium etoschense (Ciliophora) and its Systematics Enlightenment for the Class Nassophorea.

The Class Nassophorea is not monophyletic with unsolved relationship of four orders, which calls for discussion to combine morphological features and molecular phylogeny. In the present study, the ultrastructure of Apocolpodidium etoschense in the order Colpodidiida is first studied. Comparisons between orders of Nassophorea were conducted and a discussion of systematics was performed based on a SSU rRNA gene-based phylogeny. The order Colpodidiida and Nassulida shared the following features: Two pairs of alveolocysts in the cortex, the presence of a ''B-cartwheel'' in the distal region of the kinetosome, the presence of cytostomal lamellae and subcytostomal lamellae in the cytopharyngeal basket, and spindle trichocysts with a simple tip. These similarities shape a core group of Nassophorea, which are morphologically and genetically different from the order Microthoracida. Consequently, Microthoracida should be regarded as an independent taxon rather than a member of Nassophorea. Within the core group of Nassophorea, Colpodidiida as an independent order is further validated by its delicate cytopharyngeal basket which lacks nematodesmal lamellae; while the non-monophyly of the order Nassulida might be explained by differentiation of the cartwheels in kinetosomes and the arrangement of kinetosomes with postciliary microtubules in the nassulid organelle 3 within its members.

Motion robust ICG measurements using a two-step spectrum denoising method.

Objective. Impedance cardiography (ICG) is a noninvasive and continuous method for evaluating stroke volume and cardiac output. However, the ICG measurement is easily interfered due to respiration and body movements. Taking into consideration about the spectral correlations between the simultaneously collected ICG, electrocardiogram (ECG), and acceleration signals, this paper introduces a two-step spectrum denoising method to remove motion artifacts of ICG measurements in both resting and exercising scenarios.Approach. First, the major motion artifacts of ECG and ICG are separately suppressed by the spectral subtraction with respect to acceleration signals. The obtained ECG and ICG are further decomposed into two sets of intrinsic mode functions (IMFs) through the ensemble empirical mode decomposition. We then extract the shared spectral information between the two sets of IMFs using the canonical correlation analysis in a spectral domain. Finally, the ICG signal is reconstructed using those canonical variates with largest spectral correlations with ECG IMFs.Main results. The denoising method was evaluated for 30 subjects under both resting and cycling scenarios. Experimental results show that the beat contribution factor of ICG signals increases from its original 80.1%-97.4% after removing the motion artifacts.Significance. The proposed denoising scheme effectively improves the reliability of diagnosis and analysis on cardiovascular diseases relying on ICG signals.

Correction: Design and fabrication of a microfluidic chip to detect tumor markers.

[This corrects the article DOI: 10.1039/D0RA06693A.].

Performance Optimization of Microvalves Based on a Microhole Array for Microfluidic Chips.

A microfluidic chip with a microvalve based on a microhole array is proposed in this paper for the POCT of tumor marker proteins. In order to control the biochemical reaction time accurately and obtain a higher testing sensitivity, the parameters of the microhole array are optimized basing on the investigation of the effects of the variation of those parameters on the fluid rate and the residual liquid value in the microvalve region. By conducting liquid flow experiments using microvalves based on microhole arrays with varying microstructural parameters, the residual rate of reaction products is demonstrated to be proportional to the depth and diameter of the microholes and inversely proportional to the distance between the microhole centers. A comprehensive analysis indicates that a microhole depth of 95 µm, a microhole diameter of 230 µm, and a distance between microhole centers of 250 µm not only ensure a sufficiently long delay time, but also reduce the residual rate of reaction products, thereby providing an optimum microvalve performance that maximizes the detection efficiency and accuracy of microfluidic chips.

Design and fabrication of a microfluidic chip to detect tumor markers.

A microfluidic chip based on capillary infiltration was designed to detect tumor markers. Serum samples flowed along a microchannel that used capillary force to drive sample injection, biochemical reactions and waste liquid collection. This permitted us to realize rapid qualitative detection of tumor markers and other biological molecules. The chip integrated a number of microfluidic functions including blood plasma separation, microvalve operation, and antibody immobilization. Using antigen-antibody reaction principles, the chip provided highly selective and sensitive detection of markers. Combining a microfluidic chip with immunoassays not only improved the antigen-antibody reaction speed, but also reduced the consumption of samples and reagents. The experimental results showed that the chip can achieve separation of trace whole blood, control of sample flow rate, and detection of alpha fetoprotein, thus providing preliminary verification of its feasibility and potential for clinical use. In summary, in this paper a cheap, mass-produced, and portable microfluidic chip for cancer detection, which has good prospects for practical use during disease diagnosis and screening is reported.

Alterations of motor cortical microcircuit in a depressive-like mouse model produced by light deprivation.

Depression is one of the most prevalent and life-threatening forms of mental illness. The heavy social burden imposed by this disorder calls for a better understanding of its pathogenesis. Light deficiency is an important factor potentially leading to depression. However, how the light deficiency affects neural microcircuit underlying depression remains largely unknown. This study investigated the properties of morphology, electrophysiology, and synaptology of layer V pyramidal cells (L5PCs) in the motor cortex of a mouse model with depressive behavioral phenotype that was produced by light deprivation (LD). The depressive behavioral phenotype was characterized by increased immobility and decreased locomotor activity in behavioral tests. LD decreased burst firing neurons and suppressed the intrinsic excitability of L5PCs, and also reduced the neuronal morphological complexity as evidenced by simplified basal and apical dendrites. Moreover, LD reduced the synaptic connecting probability of L5PCs. These alterations of the simplified morphology, the suppressed excitability, and the reduced connecting probability of L5PCs together could well explain the depression-like behaviors of the mouse model. However, it was surprising to find that the excitatory postsynaptic potentials (EPSPs) of single L5PC connections were significantly enhanced and the paired pulse ratio (EPSP2/EPSP1) was significantly increased. These synaptological results indicate that the absolute synaptic strength of single L5PC connections was enhanced and the transmitter release probability was increased although the connections between L5PCs became sparse. Therefore, a compensation mechanism accompanied the negative changes that were consistent with the depressive behavioral phenotype. Our findings from the motor cortex of depression-like behavior mice may underlie the neural microcircuit mechanism of depression, providing insights into the pathogenesis of depression at a level of single neurons and synaptic connections.