Editors' Choice—Review—In Vivo and In Vitro Microneedle Based Enzymatic and Non-Enzymatic Continuous Glucose Monitoring Biosensors

Background: The bacterial derived flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase (FADGDH) is the most promising enzyme for the third-generation principle-based enzyme sensor for continuous glucose monitoring (CGM). Due to the ability of the enzyme to transfer electrons directly to the electrode, recognized as direct electron transfer (DET)-type FADGDH, although no investigation has been reported about DET-type FADGDH employed on a miniaturized integrated electrode. Methods: The miniaturized integrated electrode was formed by sputtering gold (Au) onto a flexible film with 0.1 mm in thickness and divided into 3 parts. After an insulation layer was laminated, 3 openings for a working electrode, a counter electrode and a reference electrode were formed by dry etching. A reagent mix containing 1.2 × 10−4 Unit of DET-type FADGDH and carbon particles was deposited. The long-term stability of sensor was evaluated by continuous operation, and its performance was also evaluated in the presence of acetaminophen and the change in oxygen partial pressure (pO2) level. Results: The amperometric response of the sensor showed a linear response to glucose concentration up to 500 mg/dL without significant change of the response over an 11-day continuous measurement. Moreover, the effect of acetaminophen and pO2 on the response were negligible. Conclusions: These results indicate the superb potential of the DET-type FADGDH-based sensor with the combination of a miniaturized integrated electrode. Thus, the described miniaturized DET-type glucose sensor for CGM will be a promising tool for effective glycemic control. This will be further investigated using an in vivo study.

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Development of an Error Model for a Factory-Calibrated Continuous Glucose Monitoring Sensor with 10-Day Lifetime

Sensors ◽

10.3390/s19235320 ◽

2019 ◽

Vol 19 (23) ◽

pp. 5320 ◽

Cited By ~ 3

Author(s):

Martina Vettoretti ◽

Cristina Battocchio ◽

Giovanni Sparacino ◽

Andrea Facchinetti

Keyword(s):

Continuous Glucose Monitoring ◽

Time Windows ◽

Glucose Monitoring ◽

Single Step ◽

Error Model ◽

Measurement Noise ◽

Calibration Error ◽

Main Components ◽

Sensor Errors

Factory-calibrated continuous glucose monitoring (FC-CGM) sensors are new devices used in type 1 diabetes (T1D) therapy to measure the glucose concentration almost continuously for 10–14 days without requiring any in vivo calibration. Understanding and modelling CGM errors is important when designing new tools for T1D therapy. Available literature CGM error models are not suitable to describe the FC-CGM sensor error, since their domain of validity is limited to 12-h time windows, i.e., the time between two consecutive in vivo calibrations. The aim of this paper is to develop a model of the error of FC-CGM sensors. The dataset used contains 79 FC-CGM traces collected by the Dexcom G6 sensor. The model is designed to dissect the error into its three main components: effect of plasma-interstitium kinetics, calibration error, and random measurement noise. The main novelties are the model extension to cover the entire sensor lifetime and the use of a new single-step identification procedure. The final error model, which combines a first-order linear dynamic model to describe plasma-interstitium kinetics, a second-order polynomial model to describe calibration error, and an autoregressive model to describe measurement noise, proved to be suitable to describe FC-CGM sensor errors, in particular improving the estimation of the physiological time-delay.

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Acute Response in vivo of a Fiber-Optic Sensor for Continuous Glucose Monitoring from Canine Studies on Point Accuracy

Sensors ◽

10.3390/s100807789 ◽

2010 ◽

Vol 10 (8) ◽

pp. 7789-7802 ◽

Cited By ~ 4

Author(s):

Kuo-Chih Liao ◽

Shih-Chieh Chang ◽

Cheng-Yang Chiu ◽

Yu-Hsiang Chou

Keyword(s):

Continuous Glucose Monitoring ◽

Fiber Optic ◽

Glucose Monitoring ◽

Fiber Optic Sensor ◽

Acute Response ◽

Optic Sensor

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Delays in Minimally Invasive Continuous Glucose Monitoring Devices: A Review of Current Technology

Journal of Diabetes Science and Technology ◽

10.1177/193229680900300528 ◽

2009 ◽

Vol 3 (5) ◽

pp. 1207-1214 ◽

Cited By ~ 110

Author(s):

D. Barry Keenan ◽

John J. Mastrototaro ◽

Gayane Voskanyan ◽

Garry M. Steil

Keyword(s):

Blood Glucose ◽

Minimally Invasive ◽

Continuous Glucose Monitoring ◽

Ex Vivo ◽

Time Lag ◽

Glucose Monitoring ◽

Time Lags ◽

Continuous Glucose Monitor ◽

Continuous Glucose Monitors

Through the use of enzymatic sensors—inserted subcutaneously in the abdomen or ex vivo by means of microdialysis fluid extraction—real-time minimally invasive continuous glucose monitoring (CGM) devices estimate blood glucose by measuring a patient's interstitial fluid (ISF) glucose concentration. Signals acquired from the interstitial space are subsequently calibrated with capillary blood glucose samples, a method that has raised certain questions regarding the effects of physiological time lags and of the duration of processing delays built into these devices. The time delay between a blood glucose reading and the value displayed by a continuous glucose monitor consists of the sum of the time lag between ISF and plasma glucose, in addition to the inherent electrochemical sensor delay due to the reaction process and any front-end signal-processing delays required to produce smooth traces. Presented is a review of commercially available, minimally invasive continuous glucose monitors with manufacturer-reported device delays. The data acquisition process for the Medtronic MiniMed (Northridge, CA) continuous glucose monitoring system—CGMS® Gold—and the Guardian® RT monitor is described with associated delays incurred for each processing step. Filter responses for each algorithm are examined using in vitro hypoglycemic and hyperglycemic clamps, as well as with an analysis of fast glucose excursions from a typical meal response. Results demonstrate that the digital filters used by each algorithm do not cause adverse effects to fast physiologic glucose excursions, although nonphysiologic signal characteristics can produce greater delays.

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