Exploring Variations in Sleep Perception: Comparative Study of Chatbot Sleep Logs and Fitbit Sleep Data.

BACKGROUND: Patient-generated health data are important in the management of several diseases. Although there are limitations, information can be obtained using a wearable device and time-related information such as exercise time or sleep time can also be obtained. Fitbits can be used to acquire sleep onset, sleep offset, total sleep time (TST), and wakefulness after sleep onset (WASO) data, although there are limitations regarding the depth of sleep and satisfaction; therefore, the patient's subjective response is still important information that cannot be replaced by wearable devices. OBJECTIVE: To effectively use patient-generated health data related to time such as sleep, it is first necessary to understand the characteristics of the time response recorded by the user. Therefore, the aim of this study was to analyze the characteristics of individuals' time perception in comparison with wearable data. METHODS: Sleep data were acquired for 2 weeks using a Fitbit. Participants' sleep records were collected daily through chatbot conversations while wearing the Fitbit, and the two sets of data were statistically compared. RESULTS: In total, 736 people aged 30-59 years were recruited for this study, and the sleep data of 543 people who wore a Fitbit and responded to the chatbot for more than 7 days on the same day were analyzed. Research participants tended to respond to sleep-related times on the hour or in 30-minute increments, and each participant responded within the range of 60-90 minutes from the value measured by the Fitbit. On average for all participants, the chat responses and the Fitbit data were similar within a difference of approximately 15 minutes. Regarding sleep onset, the participant response was 8 minutes and 39 seconds (SD 58 minutes) later than that of the Fitbit data, whereas with respect to sleep offset, the response was 5 minutes and 38 seconds (SD 57 minutes) earlier. The participants' actual sleep time (AST) indicated in the chat was similar to that obtained by subtracting the WASO from the TST measured by the Fitbit. The AST was 13 minutes and 39 seconds (SD 87 minutes) longer than the time WASO was subtracted from the Fitbit TST. On days when the participants reported good sleep, they responded 19 (SD 90) minutes longer on the AST than the Fitbit data. However, for each sleep event, the probability that the participant's AST was within ±30 and ±60 minutes of the Fitbit TST-WASO was 50.7% and 74.3%, respectively. CONCLUSIONS: The chatbot sleep response and Fitbit measured time were similar on average and the study participants had a slight tendency to perceive a relatively long sleep time if the quality of sleep was self-reported as good. However, on a participant-by-participant basis, it was difficult to predict participants' sleep duration responses with Fitbit data. Individual variations in sleep time perception significantly affect patient responses related to sleep, revealing the limitations of objective measures obtained through wearable devices.

Regulation of anti-inflammatory and antioxidant responses by methanol extract of Mikania cordata (Burm. f.) B. L. Rob. leaves via the inactivation of NF-κB and MAPK signaling pathways and activation of Nrf2 in LPS-induced RAW 264.7 macrophages.

Mikania cordata (Burm. f.) B.L. Rob. has been traditionally used in tropical countries throughout Asia and Africa to treat gastric ulcers, dyspepsia, and dysentery. However, the mechanisms responsible for its anti-inflammatory and antioxidant activities are not fully understood. Therefore, this study sought to investigate the anti-inflammatory and antioxidant effects of methanol extracts of M. cordata (MMC) on inflammation and oxidative stress in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages and elucidate its underlying regulatory mechanism. MMC significantly suppressed the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in LPS-stimulated RAW 264.7 macrophages by downregulating the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) at both the mRNA and protein levels. Moreover, MMC effectively reduced the mRNA expression levels and production of pro-inflammatory cytokines, including interleukin-6 (IL-6), IL-1ß, and tumor necrosis factor-α (TNF-α). These suppressive effects of MMC on pro-inflammatory mediators and cytokines were mediated through the inhibition of transforming growth factor beta-activated kinase 1 (TAK1), which subsequently blocked the activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs). MMC also upregulated the nuclear factor erythroid-2-related factor 2 (Nrf2) by inducing the degradation of Kelch-like ECH-related protein 1 (Keap1), an Nrf2-specific E3 ligase. Accordingly, MMC enhanced Nrf2 target gene expression of anti-oxidative regulators such as heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1). However, it had minimal effect on the DPPH radical scavenging capacity in vitro. Collectively, these findings demonstrate that MMC holds promise as a potential therapeutic agent for alleviating inflammation-related diseases and oxidative stress.

Genomic insight into the salt tolerance and proteolytic activity of Bacillus subtilis.

We assessed the salt tolerance and proteolytic activity of 40 genome-published Bacillus subtilis strains isolated from fermented Korean foods to illuminate the genomic background behind the functionality of B. subtilis in high-salt fermentation. On the basis of the salt tolerance and phenotypic proteolytic activity of the 40 strains, we selected five strains exhibiting different phenotypic characteristics. Comparative genomic analyses of these five strains provided genomic insight into the salt tolerance and proteolytic activity of B. subtilis. Two-component system (TCS) genes annotated as ybdGJK and laterally acquired authentic ATP-binding cassette (ABC) transporter system genes of tandem repeat structure might contribute to increase salt tolerance. The additional possession of gene homologs for CAAX protease family proteins and components of Clp (caseinolytic protease) complex, ATP-dependent Clp proteolytic subunit ClpP and AAA+ (ATPases associated with diverse cellular Activities) family ATPases, might determine the proteolytic activity of B. subtilis. This study established the scientific foundation for the viability and functionality of B. subtilis in high-salt fermentation.

Hydrolysis of regenerated cellulose from ionic liquids and deep eutectic solvent over sulfonated carbon catalysts.

The efficient hydrolysis of cellulose into its monomer unit such as glucose or valuable cello-oligosaccharides is the critical step for the cost-effective production of biofuels and biochemicals. However, the current cellulose hydrolysis process involves high energy-demanding pretreatment (e.g., ball-milling) and long reaction times (>24 h). Herein, we investigated the feasibility of the dissolution/regeneration (DR) of cellulose in ionic liquids (ILs) and deep eutectic solvent (DES) as an alternative to ball-milling pretreatment for the effective hydrolysis of cellulose. Because chlorine-based solvents were reported to be the most active for cellulose pretreatment, [EMIM]Cl and [DMIM]DMP were selected as the IL molecules, and choline chloride-lactic acid and choline chloride-imidazole were selected as the DES molecules. The level of the crystallinity reduction of the regenerated cellulose were analyzed using XRD and SEM measurements. The hydrolysis kinetics of the regenerated cellulose from ILs and DES were examined at 150 °C using sulfonated carbon catalysts and compared with those of the ball-milled cellulose. Overall, the cellulose pretreatment using the ILs and the DES had superior kinetics for cellulose hydrolysis to the conventional ball milling treatment, suggesting a possibility to replace the current high energy-demanding ball-milling process with the energy-saving DR process. In addition, the utilization of supercritical carbon dioxide-induced carbonic acid as an in situ acid catalyst for the enhanced hydrolysis of cellulose was presented for the first time.

Lipidomic Analysis of Cervicovaginal Fluid for Elucidating Prognostic Biomarkers and Relevant Phospholipid and Sphingolipid Pathways in Preterm Birth.

Cervicovaginal fluid (CVF) is an excellent specimen for monitoring preterm birth (PTB) as it characterizes cervical metabolites, the vaginal environment, and specific host immune responses. However, extensive lipid analysis of CVF to explain PTB has not been studied. In this study, we performed a systematic analysis combining high-throughput lipid analysis and omics to discover the unique metabolic properties of the cervix. Liquid chromatography-high resolution mass spectrometry successfully detected a total of 190 lipids in the CVF of 30 PTB and 30 term birth (TB) pregnant women. The whole lipidomics dataset analyzed by combining multivariate and univariate statistical analysis revealed 35 lipid biomarkers, including phospholipids and sphingolipids. Remarkably, sphingomyelin, which plays a physiologically essential role in sphingolipids, was significantly downregulated in PTB. Metabolic pathway study provides a close relationship between vaginal microbial organization and cell membrane formation, further supporting the robustness of our findings. Sphingolipids and phospholipids, which were determined to be important lipids for predicting PTB in our study, showed a high value of receiver operating characteristic (ROC) curve >0.7, indicating that a lipid diagnostic test and understanding the mechanism of lipids is highly related to the vaginal microbiome. Therefore, our result has high potential as a predictor of PTB.

Hepatocellular Metabolic Abnormalities Induced by Long-Term Exposure to Novel Brominated Flame Retardant, Hexabromobenzene.

Novel brominated flame retardants (NBFRs) are widely used to avoid environmental accumulation concerns and because of the regulations imposed on classical BFRs. However, recent studies have not revealed the negative effects of NBFR accumulation and exposure on humans. We conducted a metabolomics study on hexabromobenzene (HBB), one of the NBFRs, to investigate its effect on hepatocytes. Gas chromatography-mass spectrometry-based metabolite profiling was performed to observe metabolic perturbations by treating human livertissue-derived HepG2 cell lines with HBB for maximum 21 days. Metabolic pathway enrichment using 17 metabolite biomarkers determined via univariate and multivariate statistical analysis verified that long-term accumulation of HBB resulted in distinct diminution of eight amino acids and five other metabolites. Molecular docking of the biomarker-related enzymes revealed the potential molecular mechanism of hepatocellular response to HBB exposure, which disrupts the energy metabolism of hepatic cells. Collectively, this study may provide insights into the hidden toxicity of bioaccumulating HBB and unveil the risks associated with non-regulated NBFRs.

Anti-inflammatory and antioxidant activities of methanol extract of Piper betle Linn. (Piper betle L.) leaves and stems by inhibiting NF-κB/MAPK/Nrf2 signaling pathways in RAW 264.7 macrophages.

Oxidative stress and chronic inflammation are closely linked to various diseases. However, previous studies have demonstrated that plant extracts could prevent and alleviate these adverse outcomes. Piper betle Linn. (Piper betle L.) is a cosmopolitan plant that belongs to the Piperaceae family, whose leaves are edible and possess several health benefits. This study sought to characterize the anti-inflammatory and antioxidant effects of a methanol extract of Piper betle L. leaves and stems (MPBLLS). MPBLLS was found to have a dose-dependent radical scavenging effect, as demonstrated by the 2,2-diphenyl-1-picrylhydrazyl assay. Additionally, MPBLLS inhibited the lipopolysaccharide (LPS)-stimulated production of nitric oxide and prostaglandin E2 by reducing the expression of inducible nitric oxide synthase and cyclooxygenase-2 in RAW 264.7 macrophages without affecting cell viability. Furthermore, our findings suggested that the inhibitory effects of MPBLLS on pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1ß, and interleukin-6 were due to the inhibition of the nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways in LPS-treated RAW 264.7 macrophages. MPBLLS and hydroxychavicol, a major constituent of MPBLLS, suppressed LPS-induced translocation of NF-κB p65 from cytoplasm to nucleus. Interestingly, MPBLLS increased nuclear factor erythroid 2-related factor 2 (Nrf2) protein levels and transcription levels of Nrf2 target genes in a dose-dependent manner. Collectively, our findings suggest that MPBLLS could serve as a basis for the development of novel orally-administered therapies due to its inhibitory effects on oxidative and inflammatory stress. DATA AVAILABILITY: The data presented in this study are available on request from the corresponding author.

Development of a New Biomarker Model for Predicting Preterm Birth in Cervicovaginal Fluid.

Preterm birth (PTB) is a social problem that adversely affects not only the survival rate of the fetus, but also the premature babies and families, so there is an urgent need to find accurate biomarkers. We noted that among causes, eubiosis of the vaginal microbial community to dysbiosis leads to changes in metabolite composition. In this study, short chain fatty acids (SCFAs) representing dysbiosis were derivatized using (N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide, MTBSTFA) and targeted analysis was conducted in extracted organic phases of cervicovaginal fluid (CVF). In residual aqueous CVF, polar metabolites produced biochemistry process were derivatized using methoxyamine and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), and non-targeted analysis were conducted. Nine SCFAs were quantified, and 58 polar metabolites were detected in 90 clinical samples using gas chromatography/mass spectrometry (GC/MS). The criteria of statistical analysis and detection rate of clinical sample for development of PTB biomarkers were presented, and 19 biomarkers were selected based on it, consisting of 1 SCFA, 2 organic acids, 4 amine compounds, and 12 amino acids. In addition, the model was evaluated as a suitable indicator for predicting PTB without distinction between sample collection time. We hope that the developed biomarkers based on microbiota-derived metabolites could provide useful diagnostic biomarkers for actual patients and pre-pregnancy.

Expression Profile of Sorghum Genes and Cis-Regulatory Elements under Salt-Stress Conditions.

Salinity stress is one of the most important abiotic stresses that causes great losses in crop production worldwide. Identifying the molecular mechanisms of salt resistance in sorghum will help develop salt-tolerant crops with high yields. Sorghum (Sorghum bicolor (L.) Moench) is one of the world's four major grains and is known as a plant with excellent adaptability to salt stress. Among the various genotypes of sorghum, a Korean cultivar Nampungchal is also highly tolerant to salt. However, little is known about how Nampungchal responds to salt stress. In this study, we measured various physiological parameters, including Na+ and K+ contents, in leaves grown under saline conditions and investigated the expression patterns of differentially expressed genes (DEGs) using QuantSeq analysis. These DEG analyses revealed that genes up-regulated in a 150 mM NaCl treatment have various functions related to abiotic stresses, such as ERF and DREB. In addition, transcription factors such as ABA, WRKY, MYB, and bZip bind to the CREs region of sorghum and are involved in the regulation of various abiotic stress-responsive transcriptions, including salt stress. These findings may deepen our understanding of the mechanisms of salt tolerance in sorghum and other crops.

Physio-chemical and co-expression network analysis associated with salt stress in sorghum.

BACKGROUND: Abiotic stress can damage crops and reduce productivity. Among them, salt stress is related to water stress such as osmosis and ions, and like other abiotic stresses, it can affect the growth of plants by changing gene expressions. Investigating the profiles of gene expression under salt stress may help us understand molecular mechanisms of plants to cope with unfavorable conditions. RESULTS: To study salt tolerance in sorghum, physiological and comparative transcriptomic studies were performed using a Korean sorghum cultivar 'Sodamchal' which is considered sensitive to soil salinity. In this study, the samples were treated with two concentrations of NaCl [0 (control) and 150 mM], and the leaves and roots were harvested at 0, 3, and 9 days after the treatment. For the physiological study, the levels of anthocyanin, proline, reducing sugar, and chlorophyll were evaluated in the control and the treatment group at each sampling point. The results show that the cultivar 'Sodamchal' has salt-susceptible profiles. We also analyzed the transcription profile in the presence of 0 and 150 mM NaCl to confirm the candidate genes under the saline stress condition. Between the control and salt treatment, we found a total of 1506 and 1510 differentially expressed genes (DEGs) in the leaves and roots, respectively. We also built a gene co-expression network to determine the association of the candidate genes in terms of biological pathways. CONCLUSIONS: Through the co-expression network, genes related to salt stress such as AP2/ERF and Dehydrin were identified. This study provides the physiological and genic markers that could be used during intense salt stress in sorghum. These markers could be used to lay the foundation for the distribution of high-quality seeds that are tolerant to salt in the future.

Environmental exposure to lead, mercury, and cadmium is not associated with abnormal kidney function in Korean adolescents.

BACKGROUND: We aimed to elucidate the relationship between environmental exposure to lead (Pb), mercury (Hg), and cadmium (Cd) which were measured in blood and the kidney function of adolescents. METHODS: Cross-sectional study was conducted using data from the Korea National Health and Nutrition Examination Survey from 2010 to 2017. Statistical procedures were performed to analyze the Korean population of adolescents aged 12-17 years. Regression analysis was performed, and covariates included age, sex, body mass index, smoking status, and other heavy metal levels. RESULTS: The median blood levels of Pb, Hg, and Cd were 1.165 µg/dL, 1.805 µg/L, and 0.304 µg/L, respectively. Adolescents with Pb levels in the highest quartile (> 1.454 µg/dL) had a 3.35 mL/min/1.73 m2-lower estimated glomerular filtration rate using creatinine (eGFRcr) (95% confidence interval (CI), -6.03 to -0.68 mL/min/1.73 m2) compared to those in the lowest quartile (< 0.856 µg/dL) in the unadjusted model. However, there was no association between the blood Pb level and eGFRcr in the adjusted model. Levels of Hg and Cd were not associated with eGFRcr in either model. High blood levels of all three heavy metals were not associated with the risk of hypertension. CONCLUSIONS: There was no association between increased blood levels of Pb, Hg, and Cd; eGFRcr; and increased risk of hypertension in Korean adolescents who were exposed to relatively low levels of heavy metals.

Respiratory virus surveillance in Canada during the COVID-19 pandemic: An epidemiological analysis of the effectiveness of pandemic-related public health measures in reducing seasonal respiratory viruses test positivity.

BACKGROUND: Various public health measures have been implemented globally to counter the coronavirus disease 2019 (COVID-19) pandemic. The purpose of this study was to evaluate respiratory virus surveillance data to determine the effectiveness of such interventions in reducing transmission of seasonal respiratory viruses. METHOD: We retrospectively analysed data from the Respiratory Virus Detection Surveillance System in Canada, before and during the COVID-19 pandemic, by interrupted time series regression. RESULTS: The national level of infection with seasonal respiratory viruses, which generally does not necessitate quarantine or contact screening, was greatly reduced after Canada imposed physical distancing and other quarantine measures. The 2019-2020 influenza season ended earlier than it did in the previous year. The influenza virus was replaced by rhinovirus/enterovirus or parainfluenza virus in the previous year, with the overall test positivity remaining at approximately 35%. However, during the 2019-2020 post-influenza period, the overall test positivity of respiratory viruses during the COVID-19 was still low (7.2%). Moreover, the 2020-2021 influenza season had not occurred by the end of February 2021. CONCLUSION: Respiratory virus surveillance data may provide real-world evidence of the effectiveness of implemented public health interventions during the current and future pandemics.

Effect of Large Versus Small Range of Motion in the Various Intensities of Eccentric Exercise-Induced Muscle Pain and Strength.

The purpose was to investigate eccentric (ECC) exercise with full range of motion (FROM) induce a greater magnitude of delayed onset muscle soreness (DOMS), pain, functional limitations compared to partial range of motion (PROM; outer 60° of ROM). Thirty-four participants (men and women) aged between 18 and 30 years performed ECC exercise protocol on elbow and knee muscles (5 × 10 repetitions each session) using their 15%/25%/35% of maximal voluntary isometric contraction (MVIC) with PROM (week 2-4) and FROM (week 6-8). Two days a week, ECC exercises and remaining days the subjective and objective assessments were carried out (activities of daily living (ADL), pain (visual analogue scale (VAS), pain pressure threshold (PPT)), and MVIC. The ECC exercise with FROM showed moderate pain (0-3.5) in ADL (pulling a heavy object and descending stairs), VAS, and PPT for elbow extensors and knee flexors and showed a statistically significant difference (p ≤ 0.05) compared to PROM ECC protocol. The muscle strength was increased in FROM ECC exercise than PROM ECC exercise and ranged between 23.16% and 28.22%. ECC exercise performed with FROM induced a higher degree of DOMS, pain, ADL limitations than PROM. The study outcomes can be used for beginner sedentary older adults as well as young athletes.

Screening of Phosphodiesterase-5 Inhibitors and Their Analogs in Dietary Supplements by Liquid Chromatography-Hybrid Ion Trap-Time of Flight Mass Spectrometry.

An accurate and reliable method based on ion trap-time of flight mass spectrometry (IT-TOF MS) was developed for screening phosphodiesterase-5 inhibitors, including sildenafil, vardenafil, and tadalafil, and their analogs in dietary supplements. Various parameters affecting liquid chromatographic separation and IT-TOF detection were investigated, and the optimal conditions were determined. The separation was achieved on a reversed-phase column under gradient elution using acetonitrile and water containing 0.2% acetic acid at a flow rate of 0.2 mL/min. The chromatographic eluents were directly ionized in the IT-TOF system equipped with an electrospray ion source operating in the positive ion mode. The proposed screening method was validated by assessing its linearity, precision, and accuracy. Sequential tandem MS was conducted to obtain structural information of the references, and the fragmentation mechanism of each reference was proposed for providing spectral insight for newly synthesized analogs. Structural information, including accurate masses of both parent and fragment ions, was incorporated into the MSn spectral library. The developed method was successfully applied for screening adulterated dietary supplement samples.

Increasing access to oral healthcare for marriage-immigrant women in South Korea: programme design to policy recommendation.

OBJECTIVES: To examine oral health status and access to dental care among marriage-immigrant women (MIW) in South Korea (Korea). MATERIALS AND METHODS: We analysed patients' demographic information and access to dental services through the 'Family-Love Dental Program' and compared them with Korean oral health surveillance data. The 'Family-Love Dental Program' resulted from a partnership among the Korean Ministry of the Gender Equality and Family, Seoul National University Dental Hospital, and Cigna Insurance Company (registered as 'LINA' in South Korea) to increase access to oral health for MIW from 2010 to 2016. RESULTS: Over the programme duration, 1,944 MIW underwent dental examination and 1598 MIW received dental treatment. More than two-thirds of MIW (69.5%) receiving dental services were aged between 20 and 39 years. In 2016, the proportion of untreated dental caries among MIW was 54.8%, which was significantly higher than that of untreated dental caries among Korean women within the same age group (24.9%). Over the programme duration, 501 MIW (25.8%) underwent final restoration, and advanced care was provided at the Seoul National University Dental Hospital. CONCLUSION: MIW have a significantly higher number of dental caries than Korean women within the same age group. Future programmes and policies should consider specific barriers that will promote oral health parity for MIW and their children.

Association between urban green space and the risk of cardiovascular disease: A longitudinal study in seven Korean metropolitan areas.

PURPOSE: Few previous studies have investigated the association between urban green space and cardiovascular disease (CVD) within Asian populations. We aimed to determine the relationship between amount of green space in the residential environment and CVD within a large general Asian population in this population-based longitudinal study. METHODS: The study population consisted of 351,409 participants aged over 20 years extracted from the National Health Insurance Service National Sample Cohort. Data on newly-occurred CVD events were collected from hospital admission records for the period 1 January 2006 to 31 December 2013. Cox proportional hazards regression analysis was used for determining the risk of developing CVD according to urban green space coverage (% area), adjusting for a number of relevant confounders. RESULTS: Compared to those within the lowest quartile of green space coverage, those within the highest quartile of urban space had a reduced risk of total CVD (hazard ratio, HR 0.85, 95% confidence interval, CI 0.81-0.89), coronary heart disease (HR 0.83, 95% CI 0.78-0.89), acute myocardial infarction (HR 0.77, 95% CI 0.68-0.88), total stroke (HR 0.87, 95% CI 0.82-0.93) and ischemic stroke (HR 0.86, 95% CI 0.80-0.94), but not hemorrhagic stroke (HR 0.98, 95% CI 0.86-1.12). The risk-reducing effect of green space coverage was preserved after stratification according to sex, household income, and Charlson comorbidity index. CONCLUSION: Residing in urban regions with greater green space coverage may lead to a reduced risk of CVD. Urban planning intervention policies that increase urban green space coverage could help to reduce the risk of CVD.

PDMS-Parylene Hybrid, Flexible Microfluidics for Real-Time Modulation of 3D Helical Inertial Microfluidics.

Inertial microfluidics has drawn much attention for its applications for circulating tumor cell separations from blood. The fluid flows and the inertial particle focusing in inertial microfluidic systems are highly dependent on the channel geometry and structure. Flexible microfluidic systems can have adjustable 3D channel geometries by curving planar 2D channels into 3D structures, which will enable tunable inertial separation. We present a poly(dimethylsiloxane) (PDMS)-parylene hybrid thin-film microfluidic system that can provide high flexibility for 3D channel shaping while maintaining the channel cross-sectional shape. The PDMS-parylene hybrid microfluidic channels were fabricated by a molding and bonding technique using initiated chemical vapor deposition (iCVD) bonding. We constructed 3D helical inertial microfluidic channels by coiling a straight 2D channel and studied the inertial focusing while varying radius of curvature and Reynolds number. This thin film structure allows for high channel curvature and high Dean numbers which leads to faster inertial particle focusing and shorter channel lengths than 2D spiral channels. Most importantly, the focusing positions of particles and cells in the microchannel can be tuned in real time by simply modulating the channel curvature. The simple mechanical modulation of these 3D structure microfluidic systems is expected to provide unique advantages of convenient tuning of cell separation thresholds with a single device.

Rollable Microfluidic Systems with Microscale Bending Radius and Tuning of Device Function with Reconfigurable 3D Channel Geometry.

Flexible microfluidic system is an essential component of wearable biosensors to handle body fluids. A parylene-based, thin-film microfluidic system is developed to achieve flexible microfluidics with microscale bending radius. A new molding and bonding technique is developed for parylene microchannel fabrication. Bonding with nanoadhesive layers deposited by initiated chemical vapor deposition (iCVD) enables the construction of microfluidic channels with short fabrication time and high bonding strength. The high mechanical strength of parylene allows less channel deformation from the internal pressure for the thin-film parylene channel than bulk PDMS channel. At the same time, negligible channel sagging or collapse is observed during channel bending down to a few hundreds of micrometers due to stress relaxation by prestretch structure. The flexible parylene channels are also developed into a rollable microfluidic system. In a rollable microfluidics format, 2D parylene channels can be rolled around a capillary tubing working as inlets to minimize the device footprint. In addition, we show that creating reconfigurable 3D channel geometry with microscale bending radius can lead to tunable device function: tunable Dean-flow mixer is demonstrated using reconfigurable microscale 3D curved channel. Flexible parylene microfluidics with microscale bending radius is expected to provide an important breakthrough for many fields including wearable biosensors and tunable 3D microfluidics.