With the recent SARS-CoV-2 outbreak, the importance of rapid and direct detection of respiratory disease viruses has been well recognized. The detection of these viruses with novel technologies is vital in timely prevention and treatment strategies for epidemics and pandemics. Respiratory viruses can be detected from saliva, swab samples, nasal fluid, and blood, and collected samples can be analyzed by various techniques. Conventional methods for virus detection are based on techniques relying on cell culture, antigen-antibody interactions, and nucleic acids. However, these methods require trained personnel as well as expensive equipment. Microfluidic technologies, on the other hand, are one of the most accurate and specific methods to directly detect respiratory tract viruses. During viral infections, the production of detectable amounts of relevant antibodies takes a few days to weeks, hampering the aim of prevention. Alternatively, nucleic acid–based methods can directly detect the virus-specific RNA or DNA region, even before the immune response. There are numerous methods to detect respiratory viruses, but direct detection techniques have higher specificity and sensitivity than other techniques. This review aims to summarize the methods and technologies developed for microfluidic-based direct detection of viruses that cause respiratory infection using different detection techniques. Microfluidics enables the use of minimal sample volumes and thereby leading to a time, cost, and labor effective operation. Microfluidic-based detection technologies provide affordable, portable, rapid, and sensitive analysis of intact virus or virus genetic material, which is very important in pandemic and epidemic events to control outbreaks with an effective diagnosis.
Chronic kidney disease (CKD) is a high-cost disease that
affects
approximately one in ten people globally, progresses rapidly, results
in kidney failure or dialysis, and triggers other diseases. Although
clinically used serum creatinine tests are used to evaluate kidney
functions, these tests are not suitable for frequent and regular control
at-home settings that obstruct the regular monitoring of kidney functions,
improving CKD management with early intervention. This study introduced
a new electromechanical lab-on-a-chip platform for point-of-care detection
of serum creatinine levels using colorimetric enzyme-linked immunosorbent
assay (ELISA). The platform was composed of a chip containing microreservoirs,
a stirring bar coated with creatinine-specific antibodies, and a phone
to detect color generated via ELISA protocols to evaluate creatinine
levels. An electromechanical system was used to move the stirring
bar to different microreservoirs and stir it inside them to capture
and detect serum creatinine in the sample. The presented platform
allowed automated analysis of creatinine in ∼50 min down to
∼1 and ∼2 mg/dL in phosphate-buffered saline (PBS) and
fetal bovine serum (FBS), respectively. Phone camera measurements
in hue, saturation, value (HSV) space showed sensitive analysis compared
to a benchtop spectrophotometer that could allow low-cost analysis
at point-of-care.
The main purpose of this study is to present a new active mixing strategy that can be used for lab-on-a-chip applications to shorten analysis time. An electromechanical platform composed of stepper and DC motors is designed and manufactured. This platform allows rapid mixing in microwells of a polydimethylsiloxane chip for analysis. Mixing in microwells is performed with a stirring bar spun automatically using the electromechanical platform. Mixing experiments performed at different spinning speeds and different time intervals on the platform. It was observed that mixing was achieved only in 300 ms inside 100 µL microwell using 4300 revolutions per minute (rpm) spinning speeds. Hence, the proposed mixing strategy showed 200-fold faster mixing than pure diffusion-based mixing.
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