142
A. S. Cerda-Kipper and S. Hosseini
This prototype simplified the user interface with the device and was able to perform
ELISA autonomously via sequential fluid flow due to the capillary effect. This platform exhibited great potentials for its broad range of applications in biosensing due
to its flexibility of customization and the integration of detection schemes (Novo
et al. 2014).
An automated microfluidic CL immunoassay platform for quantitative detection
of ferritin was reported by Min et al. (2018). The material chosen for the microfluidic
chip was PMMA, which is bio-friendly, cost-effective, and does not interfere with the
reaction between different reagents. Laser cutting and hot press machines were used
for fabrication of microfluidic chips. The single-use microfluidic chip was composed
of three layers: the top layer with eight air holes, a pressure port, and an open hole; the
middle layer with embedded microchannels, reagent reservoirs, a reaction reservoir,
and a waste reservoir; and the bottom substrate layer. Air holes above the open
reservoirs were employed to avoid reagent contamination and to load the reagents.
Each reservoir was connected to an individual hydrophobic microchannel which was
linked to the reaction reservoir. The microchannels were connected to the U-shaped
reaction reservoir, which was in turn connected to the waste reservoir through an
S-shaped pipe. The waste reservoir was filled with filter paper to ensure the flow of
the waste liquid, otherwise the surface tension would hinder this waste into the left
chamber. The waste chamber was linked to a pressure port.
The reliability of the automated microfluidic device was tested by measuring
biomarker of ferritin by direct sandwich immunoassay. The method of acridine esterification CL was adopted to achieve the quantitative detection, and a photomultiplier
tube was used to detect photons from acridine ester in alkaline conditions. The
reagents were primarily pre-loaded into the liquid storage chamber of the chip. The
vacuum moved the reagents across the device flexibly and easily. Subsequently, the
reagents were released by the flexible vacuum suction cups that generated power by
a pneumatic pump. After sample introduction, the chip was placed into a customized
instrument in which the CL signals were obtained and processed. The suggested
LOC platform has shown advantages including accurate quantification, sensitivity,
low cost, and portability that can be promising in extreme point of care (EPOC) (Min
et al. 2018).
Hu et al. reported an entirely integrated and autonomous microfluidic CL immune
sensor for quantitative and automated detection of biomarkers including testosterone
and C-reactive protein (CRP) in clinical samples (Table 6.1). The key components
of the microfluidic device were produced by injection molding enabling low-cost
mass manufacturing of the chips. The microfluidic chip was comprised of three
layers: the top fluidic layer, the mid tinfoil layer that was patterned antibody/antigen
stripes, and the bottom substrate layer. Each reservoir was linked to a distinct connection microchannel. The design of the channels facilitated the expansion structures
to aid the operation of on-chip valves (Fig. 6.5). A through-hole was punched at
the midpoint of each expansion structure, to position the on-chip valve and that 6
microchannels converged into a zigzag microchannel, which connected to a negative
pressure port. Through injection molding the bottom and top layers were produced
by using silicon. PDMS was utilized with three parallel microchannels to prepare
A. S. Cerda-Kipper and S. Hosseini
This prototype simplified the user interface with the device and was able to perform
ELISA autonomously via sequential fluid flow due to the capillary effect. This platform exhibited great potentials for its broad range of applications in biosensing due
to its flexibility of customization and the integration of detection schemes (Novo
et al. 2014).
An automated microfluidic CL immunoassay platform for quantitative detection
of ferritin was reported by Min et al. (2018). The material chosen for the microfluidic
chip was PMMA, which is bio-friendly, cost-effective, and does not interfere with the
reaction between different reagents. Laser cutting and hot press machines were used
for fabrication of microfluidic chips. The single-use microfluidic chip was composed
of three layers: the top layer with eight air holes, a pressure port, and an open hole; the
middle layer with embedded microchannels, reagent reservoirs, a reaction reservoir,
and a waste reservoir; and the bottom substrate layer. Air holes above the open
reservoirs were employed to avoid reagent contamination and to load the reagents.
Each reservoir was connected to an individual hydrophobic microchannel which was
linked to the reaction reservoir. The microchannels were connected to the U-shaped
reaction reservoir, which was in turn connected to the waste reservoir through an
S-shaped pipe. The waste reservoir was filled with filter paper to ensure the flow of
the waste liquid, otherwise the surface tension would hinder this waste into the left
chamber. The waste chamber was linked to a pressure port.
The reliability of the automated microfluidic device was tested by measuring
biomarker of ferritin by direct sandwich immunoassay. The method of acridine esterification CL was adopted to achieve the quantitative detection, and a photomultiplier
tube was used to detect photons from acridine ester in alkaline conditions. The
reagents were primarily pre-loaded into the liquid storage chamber of the chip. The
vacuum moved the reagents across the device flexibly and easily. Subsequently, the
reagents were released by the flexible vacuum suction cups that generated power by
a pneumatic pump. After sample introduction, the chip was placed into a customized
instrument in which the CL signals were obtained and processed. The suggested
LOC platform has shown advantages including accurate quantification, sensitivity,
low cost, and portability that can be promising in extreme point of care (EPOC) (Min
et al. 2018).
Hu et al. reported an entirely integrated and autonomous microfluidic CL immune
sensor for quantitative and automated detection of biomarkers including testosterone
and C-reactive protein (CRP) in clinical samples (Table 6.1). The key components
of the microfluidic device were produced by injection molding enabling low-cost
mass manufacturing of the chips. The microfluidic chip was comprised of three
layers: the top fluidic layer, the mid tinfoil layer that was patterned antibody/antigen
stripes, and the bottom substrate layer. Each reservoir was linked to a distinct connection microchannel. The design of the channels facilitated the expansion structures
to aid the operation of on-chip valves (Fig. 6.5). A through-hole was punched at
the midpoint of each expansion structure, to position the on-chip valve and that 6
microchannels converged into a zigzag microchannel, which connected to a negative
pressure port. Through injection molding the bottom and top layers were produced
by using silicon. PDMS was utilized with three parallel microchannels to prepare