2 Bio-microelectromechanical Systems (BioMEMS) …
49
Fig. 2.11 a Variation of color according to the concentration of glucose in tear sample. b(I) Layout
of μPAD for glucose colorimetric assays and b(II) Enzymatic reaction in presence of chromogenic
reagent (TMB) for detection of glucose (Gabriel et al. 2017)
surface was modified with chitosan in order to enhance the surface attachment of
enzymes. The chitosan was first prepared in 2% (v/v) acid acetic, subsequently 2
μL of the solution was introduced to the control and detection zones and allowed to
dry. The detection zone was spotted with a chromogenic solution of 15 mM of TMB
and 120 U mL
−1 of an enzymatic mixture of GOx and 30 U mL
−1 HRP. The control
zone was only spotted with the enzymatic solution. 5 μL of sample aliquots were
introduced to the sample inlet and left to reach the detection zone under lateral flow.
This can be visualized in Fig. 2.11b. The actual colorimetric detection was done with
an office HP scanner with a 600-dpi resolution. Images were taken 15 min after sample
addition and were converted to Red–Green–Blue scale for simpler analysis within the
Corel Photo-PaintTM software. The color intensity was directly proportional to the
concentration of glucose, however, most importantly, it was compared to a personal
glucometer, and no statistical difference existed with a confidence level of 95%.
Among different μPADs, Nilghaz et al. (2015) created a compact embeddable
microfluidic cloth-based analytical device (μCAD) in order to detect glucose, nitrite
and proteins with the naked eye and with concentrations as low as 0.5 mM, 30 μM,
49
Fig. 2.11 a Variation of color according to the concentration of glucose in tear sample. b(I) Layout
of μPAD for glucose colorimetric assays and b(II) Enzymatic reaction in presence of chromogenic
reagent (TMB) for detection of glucose (Gabriel et al. 2017)
surface was modified with chitosan in order to enhance the surface attachment of
enzymes. The chitosan was first prepared in 2% (v/v) acid acetic, subsequently 2
μL of the solution was introduced to the control and detection zones and allowed to
dry. The detection zone was spotted with a chromogenic solution of 15 mM of TMB
and 120 U mL
−1 of an enzymatic mixture of GOx and 30 U mL
−1 HRP. The control
zone was only spotted with the enzymatic solution. 5 μL of sample aliquots were
introduced to the sample inlet and left to reach the detection zone under lateral flow.
This can be visualized in Fig. 2.11b. The actual colorimetric detection was done with
an office HP scanner with a 600-dpi resolution. Images were taken 15 min after sample
addition and were converted to Red–Green–Blue scale for simpler analysis within the
Corel Photo-PaintTM software. The color intensity was directly proportional to the
concentration of glucose, however, most importantly, it was compared to a personal
glucometer, and no statistical difference existed with a confidence level of 95%.
Among different μPADs, Nilghaz et al. (2015) created a compact embeddable
microfluidic cloth-based analytical device (μCAD) in order to detect glucose, nitrite
and proteins with the naked eye and with concentrations as low as 0.5 mM, 30 μM,