Interstitial fluid (ISF) can be transdermally extracted using low-frequency ultrasound and continuous vacuum pressure
on skin surface. But the tiny volume of transdermally extracted ISF makes the transdermal extraction, collection,
transport, volumetric detection and glucose concentration measurement of the ISF very difficult. Based on a microfluidic chip for transdermally extraction of interstitial fluid and a micro glucose sensor for glucose concentration measurement, a continuous glucose monitoring instrumentby ISF transdermal extraction with minimally invasive way is developed. In the paper, various parts of the device and their interface circuits are designed; the hardware and software of the instrument are built; the simulating experiments of transdermal ISF extraction, collection and volume measurement with full-thickness pig skin are performed using this integrated system; and the functionalities of this device is verified for future clinical application.
The concentration of glucose in interstitial fluid determined by using the surface plasmon resonance (SPR) biosensor
with chemical bonding D-Galactose/D-Glucose Binding Protein (GGBP) is proposed in this paper.
D-Galactose/D-Glucose Binding Protein (GGBP), a kind of protein which has the ability to absorb the glucose
specifically, is immobilized on the gold film of the SPR sensor to improve the sensitivity of glucose detecting. The
GGBPs mutated at different points have different association abilities with glucose, which bring different measurement
range and precision. So the selection of proteins is a critical problem of the determination of glucose by using SPR
biosensor. Using different mutated GGBPs, the samples with different concentrations of glucose are measured in the
experiment, and the prediction error and precision are discussed. Furthermore, the light intensity of sensor is instable, so
the baseline of SPR responses is tracked and adjusted accordingly using the methods - fixing points and fixing areas'
ratio. The experiment results show that GGBPs mutated at different points have its corresponding working curves and
different measurement precision. In conclusion, the study is significant for the application of SPR biosensor to the
minimally invasive diabetes testing and other detection of human body components.
The continuous blood glucose monitoring system using interstitial fluid (ISF) extracted by ultrasound and vacuum is
proposed in this paper. The skin impedance measurement is introduced into the system to monitor the skin permeability
variation. Low-frequency ultrasound is applied on skin surface to enhance the skin permeability by disrupting the lipid
bilayers of the stratum corneum (SC), and then ISF is extracted out of skin continuously by vacuum. The extracted ISF is
diluted and the concentration of glucose in it is detected by a biosensor and used to predict the blood glucose
concentration. The skin permeability is variable during the extraction, and its variation affects the prediction accuracy.
The skin impedance is an excellent indicator of skin permeability in that the lipid bilayers of the SC, which offer
electrical resistance to the skin, retard transdermal transport of molecules. So the skin impedance measured during the
extraction is transformed to skin conductivity to estimate correlation coefficient between skin conductivity and
permeability. Skin conductivity correlates well with skin permeability. The method and experiment system mentioned
above may be significative for improving the prediction accuracy of continuous blood glucose monitoring system.
Glucose is one of the most important substances widely contained in organism and food, thus people pay much attention
in researching and improving the way for the detection of glucose. Traditional ways, although precise and reliable when
in high concentration and large amount of sample, have unconvincing performance in detecting mixture and solution
with low concentration and micro-volume. As far as the ideal way is concerned, it should not only specifically detect the
glucose and exclude other components in solution, but also meet the need of micro-sample (approximately 5μL) and low
concentration. We introduced D-galactose/D-glucose Binding Protein (GGBP) - a kind of protein which has the ability
to absorb the glucose specifically, to construct a novel surface plasmon resonance measuring system. By immobilizing
GGBP onto the surface of the SPR sensor, we develop a new detecting system for glucose testing in mixed solution. The
experimental result indicates that compared with 0.1g/L before immobilization of GGBP, the detecting limit or the
resolution of glucose testing rises to 1mg/L after the immobilization, the system succeeds in distinguishing glucose from
other components in mixture, which reveals a bright future to apply SPR in the minimally invasive diabetes testing and
food quality control.
Prediction of blood glucose using interstitial fluid extracted by ultrasound and vacuum is proposed by the paper.
Low-frequency ultrasound with 55 KHz is applied for about 30 seconds to enhance the skin permeability to interstitial
fluid by disrupting the stratum corneum lipid bilayers and then interstitial fluid is extracted out of skin successfully by
10in.Hg vacuum for 15 minutes. The glucose concentration in the interstitial fluid is measured by an instrument with
immobilized enzyme sensor. And then a method of data analysis is set up to prediction the glucose concentration in the
blood by the measurement of the glucose concentration in the interstitial fluid. At last, Clarke Error Grid analysis is
performed to assess if the prediction accuracy could satisfy the requirements of clinical application. The whole method
and experimental system above is set up in the article and the feasibility of this way for blood glucose detecting is
primarily validated for clinical application with the requirements of bloodless, painless, continuous glucose monitoring.
Additional a prototype of miniature diabetes monitoring device with the technique of surface plasma resonance to
measure the glucose concentration in the interstitial fluid is also being developed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.