scholarly journals Microfabrication of a Device to Evaluate the Swelling of Glucose Sensitive Hydrogels Under Isochoric Conditions

2009 ◽  
Vol 3 (2) ◽  
Author(s):  
D. Barriet ◽  
R. A. Siegel
Keyword(s):  
Side Effects ◽  
Resonant Frequency ◽  
Glucose Concentration ◽  
Glucose Monitoring ◽  
Swelling Pressure ◽  
Glucose Sensing ◽  
Hydrogel Sample ◽  
Stage Of Development ◽  
Sugar Regulation ◽  
Hydrogel Swelling

Diabetes has been the focus of intense research for more than half a century both in academia and in industry. The number of diabetes cases (especially type II) continues to increase due to the obesity pandemic in western societies and the cost of treatment of diabetes and its severe side effects will undoubtedly continue to drive development of wide ranging technological means to better understand and treat diabetes. Tight blood sugar regulation has been shown to delay or limit side effects and prolong lifespan in patients. Continuous glucose monitoring (CGM) is expected to provide information that can be used in better regulating patient behavior, or as part of a closed loop feedback control system for administering insulin at appropriate times. Our approach to CGM involves a hydrogel whose swelling depends on glucose concentration, coupled to an LC microresonator circuit, whose resonant frequency depends on hydrogel swelling due to impingment of the hydrogel on one plate of the microcapacitor. The whole sensor is microfabricated and implantable. Wireless determination of the resonant frequency permits continuous glucose sensing without chronic skin breach. We are in the process of designing hydrogels that swell/shrink with decreasing/increasing glucose concentration to test for hypoglycemia or hyperglycemia. In collaboration with Professor Babak Ziaie's group at Purdue, a first generation microdevice was fabricated. Since the full sensor requires a significant investment in time and money for its fabrication, the incorporation and testing of diverse hydrogel systems in the full device is unrealistic at the present stage of development. We are currently fabricating a testbed device to allow for the selection of lead hydrogels, which will evaluate quantitatively the relationship stimuli/pressure. Few examples exist in the literature to measure the swelling pressure of hydrogels under isochoric conditions (V=constant) experimentally. We will describe our progress toward the fabrication of a test device to evaluate the pressure developed by a hydrogel sample inside a cavity. We used a commercial pressure die with a very small piezoresistive element (500μm by 500μm), and packaged it such that the pressure sensitive membrane was in contact with a hydrogel sample a few tens of μm thin separated from the external environment by a commercial Anodisc? membrane (0.02 and 0.2 μm pore diameter). Details of design and preliminary results will be presented.

Continuous glucose monitoring and haemoglobin A1c

2002 ◽  
Vol 39 (5) ◽  
pp. 516-517 ◽  
Author(s):  
Patrick Sharp ◽  
Sandra Rainbow
Keyword(s):  
Type 1 Diabetes ◽  
Monitoring System ◽  
Continuous Glucose Monitoring ◽  
Glucose Concentration ◽  
Glucose Monitoring ◽  
Glucose Sensing ◽  
Continuous Glucose Monitoring System ◽  
Blood Profile ◽  
Sensor Glucose

Background: Measurement of HbA1c is the standard test for assessment of glycaemic control in diabetic subjects. Using new glucose sensing technology we re-evaluated the significance of HbA1c in terms of the aspects of the blood profile it measures in patients with diabetes. Methods: In a group of 27 patients with type 1 diabetes, interstitial fluid glucose concentrations were monitored for a mean of 2·6 days using the Continuous Glucose Monitoring SystemTM (MiniMed Inc, CA, USA). Results were correlated with an HbA1c measurement taken at the time of sensor insertion. Results: Results were available in 25 subjects, two datasets being lost due to patient error. There was a correlation between mean sensor glucose value, and the HbA1c value ( r=0·59, P=0·002). The correlation with standard deviation of the readings was weaker (r=0·3, P=0·15). No other descriptor of the sensor glucose concentration correlated with HbA1c. Conclusion: The mean interstitial glucose concentration recorded with the Continuous Glucose Monitoring System correlates with HbA1c level recorded at the time, but with no other marker of glucose control in diabetic subjects. These results have implications for the interpretation of HbA1c concentrations in type 1 diabetes.

Accuracy and precision assessment of a new blood glucose monitoring system

2016 ◽  
Vol 54 (1) ◽  
Author(s):  
Li-Nong Ji ◽  
Li-Xin Guo ◽  
Li-Bin Liu
Keyword(s):  
Blood Glucose ◽  
Glucose Concentration ◽  
Blood Glucose Concentration ◽  
Venous Blood ◽  
Glucose Monitoring ◽  
Blood Glucose Monitoring ◽  
Blood Samples ◽  
Glucose Testing ◽  
Blood Tests ◽  
Accuracy And Precision

AbstractBlood glucose self-monitoring by individuals with diabetes is essential in controlling blood glucose levels. The International Organization for Standardization (ISO) introduced new standards for blood glucose monitoring systems (BGMS) in 2013 (ISO 15197: 2013). The CONTOUR PLUSThis study evaluated the accuracy and precision of CONTOUR PLUS BGMS in quantitative glucose testing of capillary and venous whole blood samples obtained from 363 patients at three different hospitals.Results of fingertip and venous blood glucose measurements by the CONTOUR PLUS system were compared with laboratory reference values to determine accuracy. Accuracy was 98.1% (96.06%–99.22%) for fingertip blood tests and 98.1% (96.02%–99.21%) for venous blood tests. Precision was evaluated across a wide range of blood glucose values (5.1–17.2 mmol/L), testing three blood samples repeatedly 15 times with the CONTOUR PLUS blood glucose meter using test strips from three lots. All within-lot results met ISO criteria (i.e., SD<0.42 mmol/L for blood glucose concentration <5.55 mmol/L; CV<7.5% for blood glucose concentration ≥5.55 mmol/L). Between-lot variations were 1.5% for low blood glucose concentration, 2.4% for normal and 3.4% for high.Accuracy of both fingertip and venous blood glucose measurements by the CONTOUR PLUS system was >95%, confirming that the system meets ISO 15197: 2013 requirements.

scholarly journals A Review of Non-Invasive Optical Systems for Continuous Blood Glucose Monitoring

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6820
Author(s):  
Bushra Alsunaidi ◽  
Murad Althobaiti ◽  
Mahbubunnabi Tamal ◽  
Waleed Albaker ◽  
Ibraheem Al-Naib
Keyword(s):  
Blood Glucose ◽  
Glucose Monitoring ◽  
Daily Basis ◽  
Glucose Sensing ◽  
Blood Glucose Monitoring ◽  
Optical Systems ◽  
Glucose Levels ◽  
Non Invasive ◽  
Blood Glucose Levels ◽  
Continuous Blood Glucose Monitoring

The prevalence of diabetes is increasing globally. More than 690 million cases of diabetes are expected worldwide by 2045. Continuous blood glucose monitoring is essential to control the disease and avoid long-term complications. Diabetics suffer on a daily basis with the traditional glucose monitors currently in use, which are invasive, painful, and cost-intensive. Therefore, the demand for non-invasive, painless, economical, and reliable approaches to monitor glucose levels is increasing. Since the last decades, many glucose sensing technologies have been developed. Researchers and scientists have been working on the enhancement of these technologies to achieve better results. This paper provides an updated review of some of the pioneering non-invasive optical techniques for monitoring blood glucose levels that have been proposed in the last six years, including a summary of state-of-the-art error analysis and validation techniques.

scholarly journals Accuracy of flash glucose monitoring and continuous glucose monitoring technologies: Implications for clinical practice

2018 ◽  
Vol 15 (3) ◽  
pp. 175-184 ◽  
Author(s):  
Ramzi A Ajjan ◽  
Michael H Cummings ◽  
Peter Jennings ◽  
Lalantha Leelarathna ◽  
Gerry Rayman ◽  
...  
Keyword(s):  
Continuous Glucose Monitoring ◽  
Diabetes Care ◽  
Interstitial Fluid ◽  
Glucose Monitoring ◽  
Relative Difference ◽  
Glucose Sensing ◽  
Sensor Data ◽  
Flash Glucose Monitoring ◽  
Fluid Sensor ◽  
Monitoring Technologies

Continuous glucose monitoring and flash glucose monitoring technologies measure glucose in the interstitial fluid and are increasingly used in diabetes care. Their accuracy, key to effective glycaemic management, is usually measured using the mean absolute relative difference of the interstitial fluid sensor compared to reference blood glucose readings. However, mean absolute relative difference is not standardised and has limitations. This review aims to provide a consensus opinion on assessing accuracy of interstitial fluid glucose sensing technologies. Mean absolute relative difference is influenced by glucose distribution and rate of change; hence, we express caution on the reliability of comparing mean absolute relative difference data from different study systems and conditions. We also review the pitfalls associated with mean absolute relative difference at different glucose levels and explore additional ways of assessing accuracy of interstitial fluid devices. Importantly, much data indicate that current practice of assessing accuracy of different systems based on individualised mean absolute relative difference results has limitations, which have potential clinical implications. Healthcare professionals must understand the factors that influence mean absolute relative difference as a metric for accuracy and look at additional assessments, such as consensus error grid analysis, when evaluating continuous glucose monitoring and flash glucose monitoring systems in diabetes care. This in turn will ensure that management decisions based on interstitial fluid sensor data are both effective and safe.

In vitro analysis of glucose metabolism and embryonic growth in postimplantation rat embryos

Development ◽  
1987 ◽  
Vol 100 (3) ◽  
pp. 431-439 ◽  
Author(s):  
S.K. Ellington
Keyword(s):  
Glucose Metabolism ◽  
Embryonic Development ◽  
Glucose Uptake ◽  
Glucose Concentration ◽  
Culture Media ◽  
Rat Embryos ◽  
Embryonic Growth ◽  
Stage Of Development

The glucose metabolism and embryonic development of rat embryos during organogenesis was studied using embryo culture. Glucose uptake and embryonic growth and differentiation of 10.5-day explants (embryos + membranes) were limited by the decreasing glucose concentration, but not the increasing concentration of metabolites, in the culture media during the second 24 h of a 48 h culture. No such limitations were found on the embryonic development of 9.5-day explants during a 48 h culture although glucose uptake was slightly reduced at very low concentrations of glucose. From the head-fold stage to the 25-somite stage of development, glucose uptake was characteristic of the stage of development of the embryo and not the time it had been in culture. Embryonic growth of 9.5-day explants was similar to that previously observed in vivo. Glucose uptake by 9.5-day explants was dependent on the surface area of the yolk sac and was independent of the glucose concentration in the culture media (within the range of 9.4 to 2.5 mM). The proportion of glucose converted to lactate was 100% during the first 42h of culture then fell to about 50% during the final 6h. The protein contents of both the extraembryonic membranes and the embryo were dependent on the glucose uptake.

Neonatal hyperglycemia in a preterm infant managed with a subcutaneous insulin pump

2020 ◽  
Vol 77 (10) ◽  
pp. 739-744
Author(s):  
Julia D Muzzy Williamson ◽  
Brenda Thurlow ◽  
Mohamed W Mohamed ◽  
Dacotah Yokom ◽  
Luis Casas
Keyword(s):  
Blood Glucose ◽  
Preterm Infant ◽  
Glucose Concentration ◽  
Insulin Pump ◽  
Blood Glucose Concentration ◽  
Glucose Monitoring ◽  
Regular Insulin ◽  
Central Line ◽  
Subcutaneous Insulin ◽  
Neonatal Hyperglycemia

Abstract Purpose Successful use of a subcutaneous insulin pump to administer regular insulin to a preterm infant with neonatal hyperglycemia is described. Summary A 520-g female infant born at 23 weeks’ gestational age via caesarian section was noted to have elevated blood glucose concentrations ranging up to 180 mg/dL (in SI units, 10 mmol/L) on day of life (DOL) 3 and peaking on DOL 9 at 250 mg/dL (13.9 mmol/L) despite conservative glucose infusion rates. Continuous infusion of regular insulin was begun on DOL 8 and continued through DOL 44, with an average insulin infusion rate of 0.08 units/kg/h. The patient experienced blood glucose concentration lability due to multiple factors, resulting in the need for frequent and routine blood glucose concentration monitoring to minimize hypoglycemia events. On DOL 44, a subcutaneous insulin pump was placed and used to provide diluted regular insulin (25 units/mL). After 1 week, the patient’s blood glucose concentration normalized, which led to a reduction in the frequency of glucose monitoring. After 3 weeks, insulin pump use was discontinued. The patient remained euglycemic thereafter. Conclusion The use of an insulin pump resulted in decreased blood glucose checks, discontinuation of central line access, and overall better patient care.

scholarly journals The Importance of the Mixing Energy in Ionized Superabsorbent Polymer Swelling Models

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 609
Author(s):  
Eanna Fennell ◽  
Juliane Kamphus ◽  
Jacques M. Huyghe
Keyword(s):  
Swelling Pressure ◽  
Theoretical Description ◽  
Sodium Polyacrylate ◽  
Polymer Swelling ◽  
Hybrid Finite Element Method ◽  
Mixing Energy ◽  
Mixed Hybrid Finite Element ◽  
Gel Swelling ◽  
Hydrogel Swelling ◽  
Ionic Energy

The Flory–Rehner theoretical description of the free energy in a hydrogel swelling model can be broken into two swelling components: the mixing energy and the ionic energy. Conventionally for ionized gels, the ionic energy is characterized as the main contributor to swelling and, therefore, the mixing energy is assumed negligible. However, this assumption is made at the equilibrium state and ignores the dynamics of gel swelling. Here, the influence of the mixing energy on swelling ionized gels is quantified through numerical simulations on sodium polyacrylate using a Mixed Hybrid Finite Element Method. For univalent and divalent solutions, at initial porosities greater than 0.90, the contribution of the mixing energy is negligible. However, at initial porosities less than 0.90, the total swelling pressure is significantly influenced by the mixing energy. Therefore, both ionic and mixing energies are required for the modeling of sodium polyacrylate ionized gel swelling. The numerical model results are in good agreement with the analytical solution as well as experimental swelling tests.

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