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Priyadarshini, et al.
probes with bacterial DNA for in vitro diagnostic DNA in 10 mL of buffer and 10% blood within 30
applications . Another study used a manually min and detected as low as 1 CFU bacterial using
[50]
actuated miniature 3D-printed device fabricated either PCR or quantitative PCR .
[8]
using VisiJet EX200 polymer by material jetting Electrochemical detection has also been
for rapid on-site multiplexed bacterial detection accepted as a powerful tool for bacterial and viral
using calorimetric measurement . The finger- detection in 3D-printed biomarkers by identifying
[53]
actuated pumping membrane seated on the disease-related biomarkers and environmental
pumping chamber was connected to individual hazards. A pump-free bioreactor used for
enrichment/detection chambers through serpentine electrochemical detection of Salmonella consisted
channels for bacteria detection in drinking water. of two flexible polyethylene terephthalate layers
Upon depressing and releasing the membrane, with sintered inkjet-printed electrodes directly
a vacuum pressure filled in each chamber and bonded to the channel-containing layer, forming a
sucked in the sample. The lowest detection limit of sealed microfluidic device . This high throughput
[58]
1e colony forming units (CFU)/mL was observed device accommodated immunomagnetic bacterial
6
in approximately 6 hours. Furthermore, these separation. Similarly, a material-extruded bead-
pathogen detection devices were also connected to based microfluidic chip with a three-electrode
accessories for colorimetric readout, which would setup was used for the detection of influenza
improve the limit of detection . hemagglutinin . Elsewhere, a prototype system
[54]
[51]
Some groups have resorted to combined ATP with real-time impedance measurements was used
bioluminescence and magnetic particle-based to detect phage infection of cultured Lactococcus
immunomagnetic separation for bacteria sensing. lactis . The two standard microbiological testing
[25]
This is a more rapid and efficient approach for methods used for comparison were based on
increasing the sensitivity and specificity of pathogen plaque assay and turbidity measurements. Only the
identification. A 3D-printed bioreactor with inkjet-based biosensor system showed a greater
cylindrical hollow microchannel and high-capacity sensitivity to phage infection with a response
efficient magnetic O-shaped separator (HEMOS) within the first 3 h of phage inoculation. Another
was designed for Salmonella detection in large- study described a T-junction microfluidic device
volume samples (Figure 2B). The magnet-spacer with integrated sensing electrodes developed by
feature in the central area of HEMOS maximized FDM (using ABS) for label-free counting of E.
the magnetic field, thereby allowing ultra-rapid coli cells incorporated in spherical oil droplets.
capture of 10 CFU/mL of nanocluster-immobilized Cells were counted using a single-step contactless
bacteria within 3 min . Similarly, a 3D-printed conductivity system and quantified by plate
[56]
bioreactor with helical chambers (Figure 2C) was counting method. This approach offered noticeable
developed for bioluminescent Escherichia coli (E. advantages as a single-step method with minimal
coli) detection in milk . The device enabled sheath incubation time before detection . Studies have
[7]
[59]
inlet flow for improved size-dependent separation also explored the use of 3D-printed bioreactors for
of bacteria-nanocluster complexes in the helical the culture of microbes other than bacteria, such as
microchannel. A number of studies employed algae. A material jetted milli-microfluidic device
3D-printed millifluidic platforms to process (Vero™ Black material) with growth chambers,
samples larger than 1 mL. At sub-millimeter scale, microchannels, and semi-integrated optical
recyclable, 3D-printed trapezoidal preconcentration detection system was used for algal culture . Even
[55]
chamber built by DLP (acrylic resin) was used to though the growth was unsuccessful due to poor
isolate E. coli in blood samples . Another 3D- microalgal retention resulting from photopolymer
[57]
printed millifluidic device preconcentrated bacterial incompatibility with cells, other metrics observed
DNA by sequential isolation using magnetic silica during the culture offered a mechanical perspective
beads was also developed for improved pathogen that indicated the 3D-printed architecture posed
detection in blood. This method extracted bacterial promising advantages in comparison to other
International Journal of Bioprinting (2020)–Volume 6, Issue 4 91
