44
M. A. Espinosa-Hernandez et al.
Fig. 2.7 Development of color change in the detection zone in (a) filter glass paper, b filter cellulose
paper (Matˇ ejovský and Pitschmann 2018)
Recent examples of micro paper-based devices have been composed of 96
microfluidic wells (Sun et al. 2010; Sapsford 2009; Kai 2012). Sanjay et al. (2016)
created a 56-microwell paper/PMMA hybrid microfluidic microplate for detection
of infectious diseases and other bioanalytes, such as Immunoglobulin G (IgG) and
Hepatitis B surface Antigen (HBsAg). The chip was laser cut based on the Adobe
Illustrator design. In the mask-less laser ablation, the PMMA substrate was placed
on a stage. The choice of using porous paper for the flow-through microwells in the
PAD allowed the antibodies and antigens to be quickly immobilized, washed effectively, and avoid complicated surface modifications. The microfluidic microplate was
composed of three PMMA layers, as seen in Fig. 2.8a. The first layer (Fig. 2.8bI)
consists of an inlet reservoir (Fig. 2.82.8b1) and fluid distribution channel (Fig. 2.8b3)
which was used for fluid delivery. It delivered the assay reagents to multiple microwells, which avoids manual pipetting and costly machinery, and forms the cover for
the microwells in the following layer. Every channel in the top layer was connected
to different inlet reservoirs and delivered the reagents to 7 microwells to the next
layer. The second layer (Fig. 2.8bII) was for incubation and made up of 56 2 ×
0.3 mm funnel-shaped microwells (Fig. 2.8c), with an upper microwell (Fig. 2.8b4)
and lower microwell (Fig. 2.8b6). Paper disks (Fig. 2.8b5) were placed in between
the two parts of the microwells. The microwells were created within a few minutes
with a simple laser ablation method. This method offers a quick prototyping for
developing microfluidic devices by means of high intensity laser beams that evaporate polymers at the focal point. Varying the intensity results in microstructures with
different depths. the paper was held in place and prevented backflow of reagents as it
is where the antigen or antibody were immobilized. The bottom layer (Fig. 2.8bIII)
was fluid removal by means of the outlet channel (Fig. 2.8b7) leading to a common
outlet reservoir (Fig. 2.8b8). Each channel was connected to a single outlet microwell
to act as an outlet reservoir with a negative pressure. For the color change in HBsAg,
M. A. Espinosa-Hernandez et al.
Fig. 2.7 Development of color change in the detection zone in (a) filter glass paper, b filter cellulose
paper (Matˇ ejovský and Pitschmann 2018)
Recent examples of micro paper-based devices have been composed of 96
microfluidic wells (Sun et al. 2010; Sapsford 2009; Kai 2012). Sanjay et al. (2016)
created a 56-microwell paper/PMMA hybrid microfluidic microplate for detection
of infectious diseases and other bioanalytes, such as Immunoglobulin G (IgG) and
Hepatitis B surface Antigen (HBsAg). The chip was laser cut based on the Adobe
Illustrator design. In the mask-less laser ablation, the PMMA substrate was placed
on a stage. The choice of using porous paper for the flow-through microwells in the
PAD allowed the antibodies and antigens to be quickly immobilized, washed effectively, and avoid complicated surface modifications. The microfluidic microplate was
composed of three PMMA layers, as seen in Fig. 2.8a. The first layer (Fig. 2.8bI)
consists of an inlet reservoir (Fig. 2.82.8b1) and fluid distribution channel (Fig. 2.8b3)
which was used for fluid delivery. It delivered the assay reagents to multiple microwells, which avoids manual pipetting and costly machinery, and forms the cover for
the microwells in the following layer. Every channel in the top layer was connected
to different inlet reservoirs and delivered the reagents to 7 microwells to the next
layer. The second layer (Fig. 2.8bII) was for incubation and made up of 56 2 ×
0.3 mm funnel-shaped microwells (Fig. 2.8c), with an upper microwell (Fig. 2.8b4)
and lower microwell (Fig. 2.8b6). Paper disks (Fig. 2.8b5) were placed in between
the two parts of the microwells. The microwells were created within a few minutes
with a simple laser ablation method. This method offers a quick prototyping for
developing microfluidic devices by means of high intensity laser beams that evaporate polymers at the focal point. Varying the intensity results in microstructures with
different depths. the paper was held in place and prevented backflow of reagents as it
is where the antigen or antibody were immobilized. The bottom layer (Fig. 2.8bIII)
was fluid removal by means of the outlet channel (Fig. 2.8b7) leading to a common
outlet reservoir (Fig. 2.8b8). Each channel was connected to a single outlet microwell
to act as an outlet reservoir with a negative pressure. For the color change in HBsAg,