54
M. A. Espinosa-Hernandez et al.
Fig. 2.14 Microfluidic colorimetric biosensor for detection of E. coli O157:H7 based on gold
nanoparticles and smartphone imaging (Zheng et al. 2019)
also incorporated a 14 × 14 × 1 mm chamber that separated the MNP-bacteria-PS
complexes and catalyzed hydrogen peroxide. The last part was a 14 × 14 × 2 mm
detection chamber where the AuNPs color modifications were observed. The MNPs
modified with the capture antibodies and the PSs modified with the detection antibodies were used to interact with the target bacteria in the first mixing channel. AuNP
were added for signal indication, Hue-Saturation-Lightness (HSL)-based smartphone
imaging correctly detected changes in color, and the microfluidic chip was created
for on-chip bioreaction. The results showed that the LOD was 50 CFU/mL for E.
coli O157:H7 and the mean recovery was -96.8%.
An analyzer was created by Li et al. for multi-index monitoring of diabetes and
hyperlipidemia from a patient’s blood Li et al. (2019c) The indexes for monitoring
involves glucose (GLU), triglyceride (TG), and total cholesterol (TC). The color
changes originated from the peroxidase-H 2 O 2 enzymatic reactions and were taken
with a smartphone analyzer that contained a LED light and a charge-coupled device
(CCD) camera. The smartphone-assisted microfluidic analyzer contained a 2 mm
thick structural layer made from plastic injection molding with pressure sensitive
adhesive (PSA) layers on either side. The most important piece was the fan-shaped
body of the device with 3.25 cm radius, a buffer pool, four reaction chambers with
vent holes, and two positioning holes, each with three capillary stop valves (Fig. 2.15).
The analyzer was an optical detection system based on step motor, microcontroller,
and Bluetooth module. The detection zone included a white LED, macro lens and
a CCD camera. To build the microchip, the plastic was first attached to only the
bottom layer of adhesive. Subsequently, 13 μL of each detection reagent was input
to each of three chambers, leaving one empty to serve as control. The reagents were
left there during incubation for 4 h at 37 °C and then the top adhesive was added.
M. A. Espinosa-Hernandez et al.
Fig. 2.14 Microfluidic colorimetric biosensor for detection of E. coli O157:H7 based on gold
nanoparticles and smartphone imaging (Zheng et al. 2019)
also incorporated a 14 × 14 × 1 mm chamber that separated the MNP-bacteria-PS
complexes and catalyzed hydrogen peroxide. The last part was a 14 × 14 × 2 mm
detection chamber where the AuNPs color modifications were observed. The MNPs
modified with the capture antibodies and the PSs modified with the detection antibodies were used to interact with the target bacteria in the first mixing channel. AuNP
were added for signal indication, Hue-Saturation-Lightness (HSL)-based smartphone
imaging correctly detected changes in color, and the microfluidic chip was created
for on-chip bioreaction. The results showed that the LOD was 50 CFU/mL for E.
coli O157:H7 and the mean recovery was -96.8%.
An analyzer was created by Li et al. for multi-index monitoring of diabetes and
hyperlipidemia from a patient’s blood Li et al. (2019c) The indexes for monitoring
involves glucose (GLU), triglyceride (TG), and total cholesterol (TC). The color
changes originated from the peroxidase-H 2 O 2 enzymatic reactions and were taken
with a smartphone analyzer that contained a LED light and a charge-coupled device
(CCD) camera. The smartphone-assisted microfluidic analyzer contained a 2 mm
thick structural layer made from plastic injection molding with pressure sensitive
adhesive (PSA) layers on either side. The most important piece was the fan-shaped
body of the device with 3.25 cm radius, a buffer pool, four reaction chambers with
vent holes, and two positioning holes, each with three capillary stop valves (Fig. 2.15).
The analyzer was an optical detection system based on step motor, microcontroller,
and Bluetooth module. The detection zone included a white LED, macro lens and
a CCD camera. To build the microchip, the plastic was first attached to only the
bottom layer of adhesive. Subsequently, 13 μL of each detection reagent was input
to each of three chambers, leaving one empty to serve as control. The reagents were
left there during incubation for 4 h at 37 °C and then the top adhesive was added.