Microfabrication processes:
Microfluidic testing. Assays were run consecutively. Pretreatment of sampled blood was carried out using 1 µL of proteinase K (20 mg/mL; Thermo) and also 10 µL of lysis buffer (4 M GUSCN, 25 mM sodium citrate, 0.2% SDS). The pretreatment took place in a 1.5-mL Eppendorf tube which was then incubated at 60 °C for 5 min with 10 µL of cell lysis buffer, and 1 μL of MagaZorb beads (diameter 4.5 μm) (Promega). Binding buffer (20 microliters) was added to the sample and then incubated at room temperature for a period of 5 minutes. A 40-µL of the homogenous mixture obtained was then added to the sample zone. The residue was filtered out to the waste pad while the magnetic beads were collected. The magnetic beads were then washed with a suitable buffer. The diagnostic device was folded to enable contact between the sample zone and the distributing channel. To elute the DNA, 40 µL of elution buffer (100 mM TE buffer, pH 8.0) was added. The eluted data was then directed to three locations within the wax-printed channel and transferred to reaction chambers in the plastic device. The folded paper was then disposed through incineration. An acetate was used to seal the independent chambers. Acetate was used to minimize evaporation of the liquid during the process of isothermal amplification. The LAMP isothermal reaction (n = 59) using an electric-powered hot plate was carried out. Finally, the intensity of the diagnostic test as well as control lines were analyzed and assessed utilizing image J. Further, the percentage intensity of the control line for each diagnostic test was calculated (Reboud et al., 2019).
Advantages of the devices and problems they are solving:
The paper-based microfluidic device is advantageous to people in remote places due to its rapid, DNA-based and highly sensitive molecular diagnostic. The device aids in the accurate and timely treatment of infectious diseases. One of the problems that the device seeks to address is getting rid of existing unreliable standard field techniques and tests for infections. The device therefore provides a species-specific detection method to direct therapy to reduce the burden of infections. The diagnostic tool also presents an innovative, low-cost and user-friendly device which solves the problem of complexity and centralization of laboratories (Reboud et al., 2019).
Proposed improvement to the device
To improve the device, I propose a novel microfluidic paper-based analytical device (μPAD). This device is an improved version since it utilizes the native high electroosmotic flow (EOF) to enable focusing on stationary isotachophoresis (ITP). The approach is suitable in decoupling sample accumulations leading to focus on shorter lengths of distribution channels. In this improved device, there is a balanced isotaphoresisand short paper-based microfluidic channel. The use of native high electroosmotic flow enables the device to process a 200 μL sample in about 6 min. compared to the previous device, μPAD avails a full order magnitude improvement. The device has the capacity to detect nucleic acids, with a limit-of-detection (LoD) of 5 pM in 10 minutes without the amplification-free (Rosenfeld & Bercovici, 2018).