Integration of a Nanoporous Platinum Thin Film into a Microfluidic System for Non-enzymatic Electrochemical Glucose Sensing

JOO, Segyeong,PARK, Sejin,CHUNG, Taek Dong,KIM, Hee Chan Japan Society for Analytical Chemistry 2007 Analytical sciences Vol.23 No.3

<P>In this paper, we describe an amperometric-type enzymeless glucose sensing system based on a nanoporous platinum (Pt) electrode embedded in a microfluidic chip. This microchip system is comprised of a microfluidic transport channel network and a miniaturized electrochemical cell for nonenzymatic glucose sensing. Sample and buffer solutions were transferred to the cell by programmed electroosmotic flow (EOF). A nanoporous Pt electrode with the roughness factor of 200.6 was utilized to determine glucose concentrations in phosphate buffered saline (PBS) by the direct oxidation of glucose, without any separation process. The sensitivity of the developed system is 1.65 µA cm<SUP>-2</SUP> mM<SUP>-1</SUP> in the glucose concentration range from 1 - 10 mM in PBS.</P>

In-Channel ElectrochemicalDetection in the Middle of Microchannel under High Electric Field

Kang, ChungMu,Joo, Segyeong,Bae, Je Hyun,Kim, Yang-Rae,Kim, Yongseong,Chung, Taek Dong American ChemicalSociety 2012 ANALYTICAL CHEMISTRY - Vol.84 No.2

<P>We propose a new method for performing in-channel electrochemicaldetection under a high electric field using a polyelectrolytic gelsalt bridge (PGSB) integrated in the middle of the electrophoreticseparation channel. The finely tuned placement of a gold working electrodeand the PGSB on an equipotential surface in the microchannel providedhighly sensitive electrochemical detection without any deteriorationin the separation efficiency or interference of the applied electricfield. To assess the working principle, the open circuit potentialsbetween gold working electrodes and the reference electrode at varyingdistances were measured in the microchannel under electrophoreticfields using an electrically isolated potentiostat. In addition, “in-channel”cyclic voltammetry confirmed the feasibility of electrochemical detectionunder various strengths of electric fields (∼400 V/cm). Effectiveseparation on a microchip equipped with a PGSB under high electricfields was demonstrated for the electrochemical detection of biologicalcompounds such as dopamine and catechol. The proposed “in-channel”electrochemical detection under a high electric field enables widerelectrochemical detection applications in microchip electrophoresis.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2012/ancham.2012.84.issue-2/ac2016322/production/images/medium/ac-2011-016322_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac2016322'>ACS Electronic Supporting Info</A></P>

SERS decoding of micro gold shells moving in microfluidic systems

Lee, Saram,Joo, Segyeong,Park, Sejin,Kim, Soyoun,Kim, Hee Chan,Chung, Taek Dong WILEY-VCH Verlag 2010 Electrophoresis Vol.31 No.10

<P>In this study, in situ surface-enhanced Raman scattering (SERS) decoding was demonstrated in microfluidic chips using novel thin micro gold shells modified with Raman tags. The micro gold shells were fabricated using electroless gold plating on PMMA beads with diameter of 15 μm. These shells were sophisticatedly optimized to produce the maximum SERS intensity, which minimized the exposure time for quick and safe decoding. The shell surfaces produced well-defined SERS spectra even at an extremely short exposure time, 1 ms, for a single micro gold shell combined with Raman tags such as 2-naphthalenethiol and benzenethiol. The consecutive SERS spectra from a variety of combinations of Raman tags were successfully acquired from the micro gold shells moving in 25 μm deep and 75 μm wide channels on a glass microfluidic chip. The proposed functionalized micro gold shells exhibited the potential of an on-chip microfluidic SERS decoding strategy for micro suspension array.</P>

The Korean Society of Gastroenterology& SLDDS 2051 : Slide Session ; K-MO-01 : GI Motility ; New Bolus Transit Parameter in High-Resolution Impedance Manometry: Correlation with Radionuclide Esophageal Transit Scintigraphy

( Kwi-Sook Choi ),( Segyeong Joo ),( Hwoon-Yong Jung ),( Seung-Jae Myung ),( Kee Wook Jung ),( Ho June Song ),( Seon-Ok Kim ),( Hye Ok Kim ),( So Young Seo ),( Jae Seung Kim ),( Ji Yong Ahn ),( Jeong 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1

Background: High-resolution Impedance Manometry (HRIM) is used to detect complete versus incomplete bolus transit. Three-Dimensional Volume of Inverted Impedance (VII) was developed to measure the remnant impedance volume between each swallow. However, its clinical usefulness and meaning were not fully evaluated. Radionuclide esophageal transit scintigraphy (RETS) has been used to determine bolus transit in esophageal motor disorders. Here we aimed to investigate the absolute measurement of bolus transit based on the 3-D volume of impedance and its clinical meaning by assessing its relationship with RETS. Methods: Thirty-one patients who underwent both HRIM and RETS were enrolled in this study. Twenty-nine of these patients were diagnosed with achalasia and two patients were normal. Each patient underwent HRIM using a catheter with 32 circumferential pressure and 16 impedance sensors. The impedance profi les were converted to ASCII fi les and analyzed with the MATLAB program. VII was plotted after transforming the data to a cubic spline interpolation followed by resampling the manometry position at 0.2-cm intervals. The VII between swallows was categorized into four different 5-second frames. RETS was performed by using 99mTc-DTPA, and remnant radionuclide in the lumen of esophageal body was measured at 1,5,10,15,and 20 minutes ofinterval after swallowing. Results: A total of 40 HRIM and RETS procedures were analyzed (nine patients with achalasia underwent both tests twice before and after treatment). The mean VII value of the later 15 second frames from each swallow showed a signifi cant positive correlation to the 20-minute RETS (r=0.31, P=0.04). Moreover, the mean VII value of the later 10-second frames also showed a signifi cant positive correlation to 20-minute RETS (r=0.32, P=0.04). Conclusions: The newly developed VII method may have a close relationship with the currently using RETS despite different protocols.

Silicon Micromachined Infrared Thin-Layer Cell for In Situ Spectroelectrochemical Analysis of Aqueous and Nonaqueous Solvent System

Yun, Kwang-Seok,Joo, Segyeong,Kim, Hong-Jeong,Kwak, Juhyoun,Yoon, Euisik WILEY-VCH Verlag 2005 Electroanalysis Vol.17 No.11

<P>This article reports in situ FTIR monitoring of electrochemical reactions using a silicon-based thin-layer cell realized by micromachining fabrication technologies. The proposed device contains a silicon micromachined cavity cell integrated with a gold working electrode, a counter electrode, and a Ag/AgCl reference electrode. Electrochemical, spectroscopic, and spectroelectrochemical characteristics of the fabricated cell have been experimentally measured and exhibited a comparable performance to commercialized CaF<SUB>2</SUB> thin-layer cells. In situ spectroelectrochemical characteristics have been successfully tested for both 2 mM K<SUB>3</SUB>Fe(CN)<SUB>6</SUB> in an aqueous solution and 2 mM ferrocene in a dichloromethane solution using the fabricated thin-layer cell.</P>

Predicting Responsiveness to Biofeedback Therapy Using High-resolution Anorectal Manometry With Integrated Pressurized Volume

Myeongsook Seo,Jiyoung Yoon,Kee Wook Jung,Segyeong Joo,Jungbok Lee,Kyung Min Choi,Hyo Jeong Lee,In Ja Yoon,Woojoo Noh,So Young Seo,Do Yeon Kim,Sung Wook Hwang,Sang Hyoung Park,Dong-Hoon Yang,Byong Duk 대한소화기 기능성질환∙운동학회 2022 Journal of Neurogastroenterology and Motility (JNM Vol.28 No.4

Background/Aims Biofeedback therapy is widely used to treat patients with chronic constipation, especially those with dyssynergic defecation. Yet, the utility of high-resolution manometry with novel parameters in the prediction of biofeedback response has not been reported. Thus, we constructed a model for predicting biofeedback therapy responders by applying the concept of integrated pressurized volume in patients undergoing high-resolution anorectal manometry. Methods Seventy-one female patients (age: 48-68 years) with dyssynergic defecation who underwent initial high-resolution anorectal manometry and subsequent biofeedback therapy were enrolled. The manometry profiles were used to calculate the 3-dimensional integrated pressurized volumes by multiplying the distance, time, and amplitude during simulated evacuation. Partial least squares regression was performed to generate a predictive model for responders to biofeedback therapy by using the integrated pressurized volume parameters. Results Fifty-five (77.5%) patients responded to biofeedback therapy. The responders and non-responders did not show significant differences in the conventional manometric parameters. The partial least squares regression model used a linear combination of eight integrated pressurized volume parameters and generated an area under the curve of 0.84 (95% confidence interval: 0.76-0.95, P < 0.01), with 85.5% sensitivity and 62.1% specificity. Conclusions Integrated pressurized volume parameters were better than conventional parameters in predicting the responsiveness to biofeedback therapy, and the combination of these parameters and partial least squares regression was particularly promising. Integrated pressurized volume parameters can more effectively explain the physiology of the anorectal canal compared with conventional parameters.

The Predictive Value of Intraoperative Esophageal Functional Luminal Imaging Probe Panometry in Patients With Achalasia Undergoing Peroral Endoscopic Myotomy: A Single-center Experience

Li-Chang Hsing,KyungMin Choi,Kee Wook Jung,Segyeong Joo,Nayoung Kim,Ga Hee Kim,Hee Kyong Na,Ji Yong Ahn,JeongHoon Lee,Do Hoon Kim,Kee Don Choi,Ho June Song,Gin Hyug Lee,Hwoon-Yong Jung 대한소화기 기능성질환·운동학회 2022 Journal of Neurogastroenterology and Motility (JNM Vol.28 No.3

Background/AimsWe evaluated the clinical significance and prognostic power of functional luminal imaging probe (FLIP) panometry in patients with achalasia treated with peroral endoscopic myotomy (POEM), and examined the clinical parameters associated with symptomatic improvement and the presence of contractility (POC) following POEM. MethodsWe reviewed the electronic medical records of patients with achalasia treated with FLIP panometry and POEM at a tertiary teaching hospital in Seoul, Republic of Korea. Follow-up examination was composed of esophageal manometry and questionnaires on symptoms. We analyzed the FLIP data by interpolating using the cubic spline method in MATLAB. ResultsWe retrospectively analyzed 33 men and 35 women (mean age: 52 ± 17 years), of whom 14, 39, and 15 patients were diagnosed with achalasia types I, II, and III, respectively. The FLIP panometry diagnoses were reduced esophagogastric junction opening (REO) with a retrograde contractile response (n = 43); REO with an absent contractile response (n = 5); REO with a normal contractile response (n = 11); and a retrograde contractile response (n = 9). Overall, the patients showed improvements in Eckardt scores following POEM from 6.48 ± 2.20 to 1.16 ± 1.15 (P < 0.01). Post-POEM symptomatic improvement was not significantly associated with any of the clinical parameters, including panometry diagnosis. Conversely, post-POEM POC was significantly associated with the presence of repetitive antegrade contractions and achalasia subtypes (both P < 0.01). ConclusionWhile FLIP panometry was not significantly associated with the clinical course of achalasia, FLIP panometry was associated with POC following POEM and may complement manometry in the functional evaluation of esophageal motility disorders.

Evaluation of Mobile Health Applications Developed by a Tertiary Hospital as a Tool for Quality Improvement Breakthrough

Lee, Yura,Shin, Soo-Yong,Kim, Ji-Young,Kim, Jeong Hun,Seo, Dong-Woo,Joo, Segyeong,Park, Joong-Yeol,Kim, Woo Sung,Lee, Jae-Ho,Bates, David W. Korean Society of Medical Informatics 2015 Healthcare Informatics Research Vol.21 No.4

<P><B>Objectives</B></P><P>To evaluate the mobile health applications (apps) developed by a single tertiary hospital in Korea with a particular focus on quality and patient safety.</P><P><B>Methods</B></P><P>Twenty-three mobile health apps developed by Asan Medical Center were selected for analysis after exclusion of the apps without any relationship with healthcare or clinical workflow, the apps for individual usage, and the mobile Web apps. Two clinical informaticians independently evaluated the apps with respect to the six aims for quality improvement suggested by the United States Institute of Medicine. All discrepancies were resolved after discussion by the two reviewers. The six aims observed in the apps were reviewed and compared by target users.</P><P><B>Results</B></P><P>Eleven apps targeted patients, the other 12 were designed for healthcare providers. Among the apps for patients, one app also had functions for healthcare providers. 'My cancer diary' and 'My chart in my hand' apps matched all the six aims. Of the six aims, <I>Timeliness</I> was the most frequently observed (20 apps), and <I>Equity</I> was the least observed (6 apps). <I>Timeliness</I> (10/11 vs. 10/12) and <I>Patient safety</I> (10/11 vs. 9/12) were frequently observed in both groups. In the apps for patients, <I>Patient-centeredness</I> (10/11 vs. 2/12) and <I>Equity</I> (6/11 vs. 0/12) were more frequent but <I>Efficiency</I> (5/11 vs. 10/12) was less frequent.</P><P><B>Conclusions</B></P><P>Most of the six aims were observed in the apps, but the extent of coverage varied. Further studies, evaluating the extent to which they improve quality are needed.</P>