4 Bio-microelectromechanical Systems (BioMEMS) in Bio-sensing …
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feeding section for the cultured cells. To ensure the user-friendliness of microfluidic chips, a LOC handling piece was fabricated to allow performing automated
and long-term studies outside a traditional incubator. The LOC handling platform
consisted of a metal or a plastic frame to place the devices and to clamp them in the
frame. Furthermore, it contained a heating element, that ensured a precise temperature control. Two different inserts allowed the fluidic linking of these microfluidic platforms. The authors combined luminescent oxygen sensors with marketed
polymer-based microfluidic devices for cell culture. Moreover, an integrated oxygen
monitoring was applied to study oxygen consumption of microfluidic cell culture and
to investigate the oxygen diffusion into the polymer chips. The advantage of using
the oxygen sensor spots was that the readout could take place by an optical fiber via
a contactless and contamination-free method and from outside the chip. This luminescent sensor was incorporated into the microfluidic channels, facilitating analysis
of cell culture behavior while providing control over experiments. Moreover, they
discussed with a previous experiment on cell culture experiments in microfluidics,
that the lack of nutrients decrease proliferation, since surface area to volume-ratio is a
function of cells/volume (Becker et al. 2014), hence the authors concluded that their
results evidently reveal the microfluidic devices to be promising tools for several
applications including fundamental cell–cell interactions study, analyzing signaling
pathways, drug development and toxicity studies, and in-vitro experiments with high
comparability and transferability to in-vivo tests. Therefore, the microfluidic toolbox can influence future technologies to apply microfluidics benefits to everyday cell
biology analyses (Gärtner et al. 2015).
Pfeiffer et al. described a straightforward method by mask-less photopolymerization technique for incorporating luminescent chemical sensing spots into off-the
shelf microreactors for determination of pH values and dissolved oxygen (DO) into
all-glass microfluidic reactors, that could be achieved in less than 2 h by the aim of a
microscope and a UV-LED, as suggested in Table 4.1. Even though glass microfluidic
systems demonstrate larger chemical resistance, the existing techniques are limited
since the bonding requirements of glass devices are commonly not the same as those
for prefabricated sensing platforms. Therefore, a limited number of reports for incorporation of luminescent sensors within all glass microfluidic chips can be found in the
literature (Ehgartne 2016; Lasave et al. 2015; Ungerböck et al. 2014; Mela 2005). For
that reason, a straightforward and adaptable method to integrate minor sensing structures into commercially available microreactors is of great importance. The authors
described two photopolymer compositions and demonstrated the function of the
sensing spots in the in-line monitoring of enzymatic reactions within aqueous media.
The poly (ethyleneglycol acrylate)-based sensor spots were obtained by photopolymerization of the selected oligomers in the presence of optical probes for oxygen
and pH values, respectively. For the in-line monitoring setup, the microreactors were
joined to pH sensing features where the readout took place using a charge-coupled
device camera. Moreover, a 10× objective was applied to develop the oxygen sensor
spots. The reaction could be carefully controlled by pH or oxygen measurements
of the sensors, that, in turn, avoided opposing effects on the reaction turnover and
on the downstream procedures. The shift in the phase angle of the luminescence
103
feeding section for the cultured cells. To ensure the user-friendliness of microfluidic chips, a LOC handling piece was fabricated to allow performing automated
and long-term studies outside a traditional incubator. The LOC handling platform
consisted of a metal or a plastic frame to place the devices and to clamp them in the
frame. Furthermore, it contained a heating element, that ensured a precise temperature control. Two different inserts allowed the fluidic linking of these microfluidic platforms. The authors combined luminescent oxygen sensors with marketed
polymer-based microfluidic devices for cell culture. Moreover, an integrated oxygen
monitoring was applied to study oxygen consumption of microfluidic cell culture and
to investigate the oxygen diffusion into the polymer chips. The advantage of using
the oxygen sensor spots was that the readout could take place by an optical fiber via
a contactless and contamination-free method and from outside the chip. This luminescent sensor was incorporated into the microfluidic channels, facilitating analysis
of cell culture behavior while providing control over experiments. Moreover, they
discussed with a previous experiment on cell culture experiments in microfluidics,
that the lack of nutrients decrease proliferation, since surface area to volume-ratio is a
function of cells/volume (Becker et al. 2014), hence the authors concluded that their
results evidently reveal the microfluidic devices to be promising tools for several
applications including fundamental cell–cell interactions study, analyzing signaling
pathways, drug development and toxicity studies, and in-vitro experiments with high
comparability and transferability to in-vivo tests. Therefore, the microfluidic toolbox can influence future technologies to apply microfluidics benefits to everyday cell
biology analyses (Gärtner et al. 2015).
Pfeiffer et al. described a straightforward method by mask-less photopolymerization technique for incorporating luminescent chemical sensing spots into off-the
shelf microreactors for determination of pH values and dissolved oxygen (DO) into
all-glass microfluidic reactors, that could be achieved in less than 2 h by the aim of a
microscope and a UV-LED, as suggested in Table 4.1. Even though glass microfluidic
systems demonstrate larger chemical resistance, the existing techniques are limited
since the bonding requirements of glass devices are commonly not the same as those
for prefabricated sensing platforms. Therefore, a limited number of reports for incorporation of luminescent sensors within all glass microfluidic chips can be found in the
literature (Ehgartne 2016; Lasave et al. 2015; Ungerböck et al. 2014; Mela 2005). For
that reason, a straightforward and adaptable method to integrate minor sensing structures into commercially available microreactors is of great importance. The authors
described two photopolymer compositions and demonstrated the function of the
sensing spots in the in-line monitoring of enzymatic reactions within aqueous media.
The poly (ethyleneglycol acrylate)-based sensor spots were obtained by photopolymerization of the selected oligomers in the presence of optical probes for oxygen
and pH values, respectively. For the in-line monitoring setup, the microreactors were
joined to pH sensing features where the readout took place using a charge-coupled
device camera. Moreover, a 10× objective was applied to develop the oxygen sensor
spots. The reaction could be carefully controlled by pH or oxygen measurements
of the sensors, that, in turn, avoided opposing effects on the reaction turnover and
on the downstream procedures. The shift in the phase angle of the luminescence