Formation Pattern Analysis of Spheroids Formed by a Droplet-Based Microfluidic System for Predicting the Aggressiveness of Tumor Cells.

Examining tumor heterogeneity is essential for selecting an appropriate anticancer treatment for an individual. This study aimed to distinguish low- and high-aggressive tumor cells by analyzing the formation patterns of spheroids. The droplet-based microfluidic system was employed for the formation of each spheroid from four different subtypes of breast tumor cells. Additionally, heterotypic spheroids with T lymphocytes and cancer-associated fibroblasts (CAFs) were produced, and distinctions between low- and high-aggressive tumor cells were explored through the analysis of formation patterns using circularity, convexity, and cell distributions. In both homotypic spheroids and heterotypic spheroids with T lymphocytes, spheroids formed from low-aggressive tumor cells exhibited high circularity and convexity. On the other hand, spheroids formed from high-aggressive tumor cells had relatively low circularity and convexity. In the case of heterotypic spheroids with CAFs, circularity and convexity did not exhibit clear differences between low- and high-aggressive tumor cells, but distinct variations were observed in cell distributions. CAFs and low-aggressive tumor cells were evenly distributed, whereas the CAFs were predominantly located in the inner layer, and high-aggressive tumor cells were primarily located in the outer layer. This finding can offer valuable insights into predicting the aggressiveness of unknown tumor cells.

Enhanced enrichment of collected airborne coronavirus and influenza virus samples via a ConA-coated microfluidic chip for PCR detection.

The severe acute respiratory syndrome (SARS-CoV-2) outbreak triggered global concern and emphasized the importance of virus monitoring. During a seasonal influenza A outbreak, relatively low concentrations of 103-104 viral genome copies are available per 1 m3 of air, which makes detection and monitoring very challenging because the limit of detection of most polymerase chain reaction (PCR) devices is approximately 103 viral genome copies/mL. In response to the urgent need for the rapid detection of airborne coronaviruses and influenza viruses, an electrostatic aerosol-to-hydrosol (ATH) sampler was combined with a concanavalin A (ConA)-coated high-throughput microfluidic chip. The samples were then used for PCR detection. The results revealed that the enrichment capacity of the ATH sampler was 30,000-fold for both HCoV-229E and H1N1 influenza virus, whereas the enrichment capacities provided by the ConA-coated microfluidic chip were 8-fold and 16-fold for HCoV-229E and H1N1 virus, respectively. Thus, the total enrichment capacities of our combined ATH sampler and ConA-coated microfluidic chip were 2.4 × 105-fold and 4.8 × 105-fold for HCoV-229E and H1N1 virus, respectively. This methodology significantly improves PCR detection by providing a higher concentration of viable samples.

E2E-BPF microscope: extended depth-of-field microscopy using learning-based implementation of binary phase filter and image deconvolution.

Several image-based biomedical diagnoses require high-resolution imaging capabilities at large spatial scales. However, conventional microscopes exhibit an inherent trade-off between depth-of-field (DoF) and spatial resolution, and thus require objects to be refocused at each lateral location, which is time consuming. Here, we present a computational imaging platform, termed E2E-BPF microscope, which enables large-area, high-resolution imaging of large-scale objects without serial refocusing. This method involves a physics-incorporated, deep-learned design of binary phase filter (BPF) and jointly optimized deconvolution neural network, which altogether produces high-resolution, high-contrast images over extended depth ranges. We demonstrate the method through numerical simulations and experiments with fluorescently labeled beads, cells and tissue section, and present high-resolution imaging capability over a 15.5-fold larger DoF than the conventional microscope. Our method provides highly effective and scalable strategy for DoF-extended optical imaging system, and is expected to find numerous applications in rapid image-based diagnosis, optical vision, and metrology.

An all-in-one platform to deplete pathogenic bacteria for rapid and safe enrichment of plant-derived extracellular vesicles.

Plant-derived extracellular vesicles (PDEVs) have exhibited several advantages, such as high biocompatibility, improvement of skin conditions, and the prevention of skin aging. However, traditional methods of extraction for plant substances, such as heating under reflux or solvent extraction, are complicated, time-consuming, and low in purity. Accordingly, a simple and efficient platform is necessary for purely isolating natural substances from plants. In this study, we report a newly designed platform for removing impurities to purify PDEVs. The proposed platform comprises three parts: (i) inflow of samples, (ii) depletion of impurities, and (iii) collection of PDEVs. The platform is designed to flow from top to bottom using gravity without the need for electric components. The platform allows the delimitation of impurities, such as the pathogenic bacteria in PDEVs, by capturing magnetic beads coated with Concanavalin A (Con A). We validate the practicality of our platform using extracellular vesicles derived from liquorice (LdEVs). Notably, the LdEVs purified using the Con A-coated magnetic beads provide better cell uptake and wound recovery than the commercialized extract LdEVs. This highlights the therapeutic potential of fresh LdEVs purified using our platform, particularly in preventing skin aging. The findings of this study hold significant practical implications for the cosmeceutical and therapeutic field, providing a promising approach for the extraction and purification of natural substances from plants to harness their benefits effectively.

Electrochemical detection and analysis of tumor-derived extracellular vesicles to evaluate malignancy of pancreatic cystic neoplasm using integrated microfluidic device.

Tumor-derived extracellular vesicles (tdEVs) are one of the most promising biomarkers for liquid biopsy-based cancer diagnostics, owing to the expression of specific membrane proteins of their cellular origin. The investigation of epithelial-to-mesenchymal transition (EMT) in cancer using tdEVs is an alternative way of evaluating the risk of malignancy transformation. An ultra-sensitive selection and detection methodology is an essential step in developing a tdEVs-based cancer diagnostic device. In this study, we developed an indium-tin-oxide (ITO) sensor integrated microfluidic device consisting of two main parts: 1) a multi-orifice flow-fractionation (MOFF) channel for extraction of pure EVs by removing blood cellular debris, and 2) an ITO sensor coupled with a geometrically activated surface interaction (GASI) channel for enrichment and quantification of tdEV. The microfluidic channel and the ITO sensors are assembled with a 3D printed magnetic housing to prevent sample leakage and to easily attach/detach the sensors to/from the microfluidic channel. The tdEVs were successfully captured on the specific antibody modified ITO surfaces in the integrated microfluidic channel. The integrated sensors showed an excellent linear response between 103 and 109 tdEVs/mL. Simultaneous evaluation of the epithelial and mesenchymal markers on the tdEV surfaces successfully revealed the EMT index of the corresponding pancreatic cancer cells. Our ITO sensor integrated microfluidic device showed excellent detection in the clinically relevant tdEVs-concentration range for patients with pancreatic cystic neoplasms. Hence, this system is expected to open a new avenue for liquid biopsy-based cancer prognostics and diagnostics.

Modularized dynamic cell culture platform for efficient production of extracellular vesicles and sequential analysis.

Extracellular vesicles (EVs) are nanometer-sized particles naturally secreted by cells for intercellular communication that encapsulate bioactive cargo, such as proteins and RNA, with a lipid bilayer. Tumor cell-derived EVs (tdEVs) are particularly promising biomarkers for cancer research because their contents reflect the cell of origin. In most studies, tdEVs have been obtained from cancer cells cultured under static conditions, thus lacking the ability to recapitulate the microenvironment of cells in vivo. Recent developments in perfusable cell culture systems have allowed oxygen and a nutrient gradient to mimic the physiological and cellular microenvironment. However, as these systems are perfused by circulating the culture medium within the unified structure, independently harvesting cells and EVs at each time point for analysis presents a limitation. In this study, a modularized cell culture system is designed for the perfusion and real-time collection of EVs. The system consists of three detachable chambers, one each for fresh medium, cell culture, and EV collection. The fresh medium flows from the medium chamber to the culture chamber at a flow rate controlled by the hydraulic pressure injected with a syringe pump. When the culture medium containing EVs exceeds a certain volume within the chamber, it overflows into the collection chamber to harvest EVs. The compact and modularized chambers are highly interoperable with conventional cell culture modalities used in the laboratory, thus enabling various EV-based assays.

Coil spring-powered pump with inertial microfluidic chip for size-based isolation and enrichment of biological cells.

Microfluidic chips have been widely used for in vitro diagnostics using pretreatment of biological samples; however, biologists and clinical researchers have difficulties using them in resource-limited settings. Sample injection systems for microfluidic chips are bulky, expensive, electricity-powered, and complex. A coiled spring-powered device, which can be used to isolate variously sized cells with high efficiency continuously and passively, was developed for portable, low-cost, electricity-free, and simple sample injection. The flow driving power was provided by releasing the compression spring in the mechanical syringe driver with a one-click action. In general, a syringe pump generates a stable passive flow rate. However, the syringe pumps are large in size and expensive because they have many functions such as infusion/withdrawal flow injection and the use of syringes of various sizes, allowing them to be applied in a variety of applications performed in the laboratory. In addition, it is not suitable for portable devices because of the considerable amount of electric power required. To overcome these drawbacks, we developed a device prototype that sorts different-sized particles and separates rare tumor cells or blood cells from blood with high efficiency. The performance of the coiled spring-powered device was evaluated and found to be comparable with that of syringe pump-powered devices. In situations where trained personnel cannot handle microfluidic chips for isolating circulating biomarkers (CTCs, WBCs, or plasma) from blood samples, the coiled spring-powered device can provide diagnostic tools, especially in resource-limited countries.

Simple ultrasensitive electrochemical detection of the DBP plasticizer for the risk assessment of South Korean river waters.

Rapid detection of contaminants for the purpose of sensitive and quantitative monitoring of environmental hazards is an essential first step in realizing the avoidance of human health risks. In this regard, we present a fast and simple electrochemical method of detecting di-n-butyl phthalate (DBP) from river water samples using a phthalic acid group specific aptamer modified on a gold nanoparticle (AuNP) functionalized graphene oxide nano-platelet (GO) and ionic liquid (IL) nanocomposite. Here, the IL/GO nanocomposite allows an enhanced interaction with phthalate esters, thereby increasing the sensitivity of the sensor surface. The proposed sensor showed a wide linear dynamic range from 0.14 pg mL-1 to 0.35 ng mL-1 and from 0.35 ng mL-1 to 7 ng mL-1 with a detection limit of ≤0.042 pg mL-1, which were evaluated using standard, analytical grade DBP; the limit of quantification was determined using different concentrations of DBP in DI water in comparison with gas chromatography-mass spectroscopy (GC/MS) values. The proposed sensor was used to monitor the DBP concentrations in river water samples collected from various locations across South Korea. The quantitative data from the measurements in comparison with standard GC/MS values were then used to ascertain the human health risk posed by the daily consumption of these river waters.

A modular microfluidic platform for serial enrichment and harvest of pure extracellular vesicles.

Extracellular vesicles (EVs) are recognized as promising biomarkers for several diseases. However, their conventional isolation methods have several drawbacks, such as poor yields, low purity, and time-consuming operations. Therefore, a simple, low-cost, and rapid microfluidic platform has been extensively developed to meet the requirement in biomedical applications. Herein, a modular microfluidic platform is demonstrated to isolate and enrich EVs directly from plasma, in a combination of continuous capture and purification of EVs. The EVs were selectively captured by target-specific antibody-coated beads in a horseshoe-shaped orifice micromixer (HOMM) chip within 2 min. A fish-trap-shaped microfilter unit was subsequently used to elute and purify the affinity-induced captured EVs from the microbeads. The ability of the modular chip to capture, enrich, and release EVs was demonstrated in 5 min (100 µL sample) at high throughput (100 µL min-1). The two chips can be modularized or individually operated, depending on the clinical applications such as diagnostics and therapeutics. For the diagnostic applications, the EVs on microbeads can be directly subjected to the molecular analysis whereas the pure EVs should be released from the microbeads for the therapeutic treatments. This study reveals that the fabricated modular chip can be appropriately employed as a platform for EV-related research tools.

Electrochemical biosensor for nucleic acid amplification-free and sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA via CRISPR/Cas13a trans-cleavage reaction.

The outbreak of the COVID-19 pandemic has led to millions of fatalities worldwide. For preventing epidemic transmission, rapid and accurate virus detection methods to early identify infected people are urgently needed in the current situation. Therefore, an electrochemical biosensor based on the trans-cleavage activity of CRISPR/Cas13a was developed in this study for rapid, sensitive, and nucleic-acid-amplification-free detection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein, a redox probe conjugated with ssRNA is immobilized on the electrode surface modified with a nanocomposite (NC) and gold nanoflower (AuNF) for enhancing the sensing performance. The SARS-CoV-2 RNA is captured by the Cas13a-crRNA complex, which triggers the RNase function of Cas13a. The enzymatically activated Cas13a-crRNA complex is subsequently introduced to the reRNA-conjugated electrochemical sensor, and consequently cleaves the reRNA. A change in current occurs due to the release of the redox molecule labeled on the reRNA, which is trans-cleaved from the Cas13a-crRNA complex. The biosensor can detect as low as 4.4 × 10-2 fg/mL and 8.1 × 10-2 fg/mL of ORF and S genes, respectively, over a wide dynamic range (1.0 × 10-1 to 1.0 × 105 fg/mL). Moreover, the biosensor was evaluated by measuring SARS-CoV-2 RNA spiked in artificial saliva. The recovery of the developed sensor was found to be in an agreeable range of 96.54-101.21%. The designed biosensor lays the groundwork for pre-amplification-free detection of ultra-low concentrations of SARS-CoV-2 RNA and on-site and rapid diagnostic testing for COVID-19.

Multi-miRNA panel of tumor-derived extracellular vesicles as promising diagnostic biomarkers of early-stage breast cancer.

Extracellular vesicles (EV) have been emerging as potential biomarkers for disease monitoring. In particular, tumor-derived EV (TDE) are known to carry oncogenic miRNA, so they can be used for diagnosis of early cancer by analyzing the expression levels of EV-miRNA circulating in the blood. Here, using our novel microfluidic device, we rapidly and selectively isolate cancerous EV expressing breast cancer-derived surface markers CD49f and EpCAM within 2 minutes. Based on seven candidates of miRNA nominated from The Cancer Genome Atlas (TCGA) database, the expression levels of miRNA in TDE were validated in a total of 82 individuals, including 62 breast cancer patients and 20 healthy controls. Among seven candidates, four miRNAs (miR-9, miR-16, miR-21, and miR-429) from the EV were highly elevated in early-stage breast cancer patients compared with healthy donors. The combination of significant miRNAs from specific EV has high sensitivities of 0.90, 0.86, 0.88, and 0.84 of the area under the receiver operating characteristic curve (AUC) in each subtype (luminal A, luminal B, HER-2, and triple-negative) of early-stage breast cancer. Our results suggest that the combination of four miRNA signatures of specific EV could serve as a sensitive and specific biomarker and enable early diagnosis of breast cancer using liquid biopsy.

Circulating miR-122-5p and miR-375 as Potential Biomarkers for Bone Mass Recovery after Parathyroidectomy in Patients with Primary Hyperparathyroidism: A Proof-of-Concept Study.

Primary hyperparathyroidism (PHPT) is the leading cause of secondary osteoporosis. Although bone mineral density (BMD) tends to recover after parathyroidectomy in PHPT patients, the degree of recovery varies. Circulating microRNAs (miRNAs) profiles are known to be correlated with osteoporosis and fracture. We aimed to investigate whether osteoporotic fracture-related miRNAs are associated with postoperative BMD recovery in PHPT. Here, 16 previously identified osteoporotic fracture-related miRNAs were selected. We analyzed the association between the preoperative level of each miRNA and total hip (TH) BMD change. All 12 patients (among the 18 patients enrolled) were cured of PHPT after parathyroidectomy as parathyroid hormone (PTH) and calcium levels were restored to the normal range. Preoperative miR-19b-3p, miR-122-5p, and miR-375 showed a negative association with the percent changes in TH BMD from baseline. The association remained robust for miR-122-5p and miR-375 even after adjusting for sex, age, PTH, and procollagen type 1 N-terminal propeptide levels in a multivariable model. In conclusion, preoperative circulating miR-122-5p and miR-375 levels were negatively associated with TH BMD changes after parathyroidectomy in PHPT patients. miRNAs have the potential to serve as predictive biomarkers of treatment response in PHPT patients, which merits further investigation.

Microfluidic chip for rapid and selective isolation of tumor-derived extracellular vesicles for early diagnosis and metastatic risk evaluation of breast cancer.

The epithelial-to-mesenchymal transition (EMT) index in cancer is a complementary approach for estimating metastatic risk. Considering the demand for evaluating metastatic risk based on liquid biopsies, tumor-derived extracellular vesicles (EVs) can be exploited to generate the EMT index. For the generation of EVs-based EMT index, it is essential to selectively isolate each epithelial cell and mesenchymal cell-derived EVs. This study proposes a novel microfluidic chip for selectively separating two types of EVs in an efficient and timely manner. The microfluidic chip is fully integrated with a micromixer for the creation of efficient collision between EVs and specific antibody-coated microbeads (7 and 15 µm in diameter) and a hydrodynamic particle separator for the stratification of EVs bound microbeads according to the sizes of microbeads. Using this chip, over 90% of EVs expressing the epithelial marker (epithelial cell adhesion molecule, EpCAM) and the mesenchymal marker (CD49f) can be selectively isolated within 6.7 min per 100 µL of sample volume. The clinical relevance of EMT is investigated using plasma samples from 20 breast cancer patients and 10 age-matched controls. The EMT index produced from the microfluidic chip is in a good agreement with the conventional tissue-based EMT index and is significantly high in patients with aggressive breast cancer subtypes, compared with healthy controls. In addition, the patients with high scores on the EMT index (≥5) shows recurrence within 5 years after adjuvant treatment. Predicting EMT-index-based metastatic risk using our microfluidic chip can be beneficial for cancer diagnosis and prognosis.

Microfluidic recapitulation of circulating tumor cell-neutrophil clusters via double spiral channel-induced deterministic encapsulation.

Circulating tumor cell (CTC)-neutrophil clusters are highly potent precursors of cancer metastasis. However, their rarity in patients' blood has restricted research thus far, and moreover, studies on in vitro methods for mimicking cell clusters have generally neglected in vivo conditions. Here, we introduce an inertial-force-assisted droplet microfluidic chip that allows the recapitulation of CTC-neutrophil clusters in terms of physical as well as biochemical features. The deterministic encapsulation of cells via double spiral channels facilitates the pairing of neutrophils and cancer cells with ratios of interest (from 1 : 1 to 1 : 3). The encapsulated cells are spontaneously associated to form clusters, achieving the physical emulation of CTC-neutrophil clusters. Furthermore, the molecular signatures of CTC-neutrophil clusters (e.g., their E-cadherin, VCAM-1, and mRNA expressions) were well defined. Our novel microfluidic platform for exploring CTC-neutrophil clusters can therefore play a promising role in cancer-metastasis studies.

Salivary biomarkers in oral squamous cell carcinoma.

In disease diagnostics and health surveillance, the use of saliva has potential because its collection is convenient and noninvasive. Over the past two decades, the development of salivary utilization for the early detection of cancer, especially oral cavity and oropharynx cancer has gained the interest of the researcher and clinician. Until recently, the oral cavity and oropharynx cancers are still having a five-year survival rate of 62%, one of the lowest in all major human cancers. More than 90% of oral cancers are oral squamous cell carcinoma (OSCC). Despite the ease of accessing the oral cavity in clinical examination, most OSCC lesions are not diagnosed in the early stage, which is suggested to be the main cause of the low survival rate. Many studies have been performed and reported more than 100 potential saliva biomarkers for OSCC. However, there are still obstacles in figuring out the reliable OSCC salivary biomarkers and the clinical application of the early diagnosis protocol. The current review article discusses the emerging issues and is hoped to raise awareness of this topic in both researchers and clinicians. We also suggested the potential salivary biomarkers that are reliable, specific, and sensitive for the early detection of OSCC.

Soft, skin-interfaced microfluidic systems with integrated immunoassays, fluorometric sensors, and impedance measurement capabilities.

Soft microfluidic systems that capture, store, and perform biomarker analysis of microliter volumes of sweat, in situ, as it emerges from the surface of the skin, represent an emerging class of wearable technology with powerful capabilities that complement those of traditional biophysical sensing devices. Recent work establishes applications in the real-time characterization of sweat dynamics and sweat chemistry in the context of sports performance and healthcare diagnostics. This paper presents a collection of advances in biochemical sensors and microfluidic designs that support multimodal operation in the monitoring of physiological signatures directly correlated to physical and mental stresses. These wireless, battery-free, skin-interfaced devices combine lateral flow immunoassays for cortisol, fluorometric assays for glucose and ascorbic acid (vitamin C), and digital tracking of skin galvanic responses. Systematic benchtop evaluations and field studies on human subjects highlight the key features of this platform for the continuous, noninvasive monitoring of biochemical and biophysical correlates of the stress state.

Detachable microfluidic device implemented with electrochemical aptasensor (DeMEA) for sequential analysis of cancerous exosomes.

The quantification of cancer-derived exosomes has a strong potential for minimally invasive diagnosis of cancer during its initial stage. As cancerous exosomes form a small fraction of all the exosomes present in blood, ultra-sensitive detection is a prerequisite for the development of exosome-based cancer diagnostics. Herein, a detachable microfluidic device implemented with an electrochemical aptasensor (DeMEA) is introduced for highly sensitive and in-situ quantification of cancerous exosomes. To fabricate the aptasensor, a nanocomposite was applied on the electrode surface followed by electroplating of gold nanostructures. Subsequently, an aptamer against an epithelial cell adhesion molecule is immobilized on the electrode surface to specifically detect cancer-specific exosomes. A microfluidic vortexer is then constructed and implemented in the sensing system to increase the collision between the exosomes and sensing surface using hydrodynamically generated transverse flow. The microfluidic vortexer was integrated with the aptasensor via a 3D printed magnetic housing. The detachable clamping of the two different devices provides an opportunity to subsequently harvest the exosomes for downstream analysis. The DeMEA has high sensitivity and specificity with an ultra-low limit of detection of 17 exosomes/µL over a wide dynamic range (1 × 102 to 1 × 109) exosomes/µL in a short period. As proof of the concept, the aptasensor can be separated from the 3D printed housing to harvest and analyze the exosomes by real-time polymerase chain reaction. Moreover, the DeMEA quantifies the exosomes from plasma samples of patients with breast cancer at different stages of the disease. The DeMEA provides a bright horizon for the application of microfluidic integrated biosensors for the early detection of cancerous biomarkers.

All-in-one platform for salivary cotinine detection integrated with a microfluidic channel and an electrochemical biosensor.

Medical disorders caused by second-hand smoke are a major public health concern worldwide. To estimate the level of second-hand smoke exposure, salivary diagnostics for cotinine analysis is a compelling alternative in conventional diagnostics using bio-fluids, such as blood and urine, owing to its simple and non-invasive collection method. However, there are several critical issues, such as tedious multisteps, demand for expertise, and field unavailability to collect and transport the purified saliva for further analysis. Here, an all-in-one platform is presented to simply collect real human saliva and directly deliver it onto the biosensing surface. The platform consists of a commercial cotton-swab-type collector, 3D-printed housing, and microfluidic channel integrated with an electrochemical competitive immunosensor to evaluate the level of salivary cotinine. The immunosensor is based on a competitive binding assay between cotinine-conjugated horseradish peroxidase (C-HRP) and cotinine for anti-cotinine binding sites. The current responses obtained from the HRP-thionine-H2O2 system decreased proportionally to the cotinine concentration. This immunosensor successfully detected its target over a range of 1 × 10-1 to 1 × 104 pg ml-1 with a low limit of detection of 6 × 10-2 pg ml-1 and a limit of quantification of 1 × 10-1 pg ml-1. In addition, the platform is applicable to various commercial cotton-swab-type saliva collectors and can successfully transfer the saliva in wide flow rates ranging from 0.1 to 30 ml min-1 without leakage or damage to the sensing surface. Furthermore, the practicality of the proposed platform was evaluated by measuring cotinine in real human saliva from eight non-smokers. The concentration of cotinine was from 45.7 to 890.8 pg ml-1, which was in good agreement with that measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The introduced all-in-one platform represented a reliable performance delivering simple and practical steps in salivary diagnostics.

Automatically Controlled Microfluidic System for Continuous Separation of Rare Bacteria from Blood.

Bloodstream infection by microorganisms is a major public health concern worldwide. Millions of people per year suffer from microbial infections, and current blood culture-based diagnostic methods are time-consuming because of the low concentration of infectious microorganisms in the bloodstream. In this study, we introduce an efficient automated microfluidic system for the continuous isolation of rare infectious bacteria (Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) from blood. Bacteria received a balanced force between a fluidic drag force and a periodically controlled dielectrophoretic (DEP) force from tilted electrodes to minimize cell adhesion to the electrodes, which prevented the loss of rare infectious bacteria. Target bacteria were efficiently segregated from the undesired blood cells to ensure that only the bacteria received the DEP force under the hypotonic condition, while the blood cells received no DEP force and exited the channel via a laminar flow. Thus, the bacteria were successfully extracted from the blood with a high recovery yield of 91.3%, and the limit of the bacteria concentration for isolation was 100 cfu/ml. We also developed an automated system that performed every step from blood-sample loading to application of electricity to the microfluidic chip for bacteria separation. It reduced the standard deviation of the bacteria recovery yield from 6.16 to 2.77 compared with the conventional batch process, providing stable bacteria-extraction performance and minimizing errors and bacteria loss caused by user mistakes. © 2019 International Society for Advancement of Cytometry.

Smart Fatigue Phone: Real-time estimation of driver fatigue using smartphone-based cortisol detection.

Numerous studies reported that psychological fatigue is one of the main reasons leading fatal road crashes. In order to quantify fatigue level of each subject, we measured a concentration of salivary cortisol from 4 subjects (20-40 years of age) using the Smart Fatigue Phone, which consists of a lateral flow immunosensor and a smartphone-linked fluorescence signal reader, during 50-min driving session. Since the salivary cortisol needs to be measured below 1 ng/mL to distinguish the subjects from awaken-drivers, we have employed the fluorescence detection module (Limit of detection: 0.1 ng/mL). To validate correlation between fatigue status and salivary cortisol concentration measured by the Smart Fatigue Phone, the electroencephalogram (EEG) signal was simultaneously obtained from the participants. As a result, alpha wave and concentration of cortisol over time was highly correlated, reflecting that quantification of salivary cortisol can be used for real-time monitoring of driver fatigue (p < 0.05). The Smart Fatigue Phone is expected to be a useful tool for drivers to recognize their fatigue status and subsequently to make a decision for driving a car. Thus, we assume that this fatigue detection system will consequently minimize road crashes by quantifying salivary cortisol in real time in the near future.