A pocket-size fluorimeter produced results broadly comparable with larger laboratory instruments across several rapid molecular tests, according to a proof-of-concept study published in IEEE Sensors Journal.
VPodDuo measures the fluorescent signals generated when a molecular assay identifies its target. Its two ports allow a test sample and negative control to be assessed simultaneously under the same conditions, helping distinguish target-related fluorescence from background signals.
The researchers evaluated the system with reverse transcription loop-mediated isothermal amplification, recombinase polymerase amplification, clustered regularly interspaced short palindromic repeats (CRISPR)-based assays, and a nonenzymatic amplification method. Testing covered nucleic acid targets associated with Zika virus, methicillin-susceptible Staphylococcus aureus, human immunodeficiency virus, and lung cancer. Assay reactions lasted approximately 10 minutes.
For Zika virus, VPodDuo and a QuantStudio laboratory instrument both achieved a detection limit of 10,000 copies/µL. For methicillin-susceptible S aureus, the respective detection limits were 100 copies/µL and 10 copies/µL.
In CRISPR-based testing, VPodDuo identified a human immunodeficiency virus target at approximately 7 pM, compared with 8 pM using a laboratory microplate reader. It identified the L858R epidermal growth factor receptor mutation, which is associated with non-small cell lung cancer, at approximately 29 pM, compared with 47 pM using the laboratory reader.
The researchers also assessed miR-375-3p, a microRNA associated with small cell lung cancer. VPodDuo and a commercial Qubit fluorimeter both achieved a detection limit of 500 pM. In further testing, the portable system distinguished positive samples from negative controls at temperatures ranging from 21 °C to 30 °C, including in an outdoor setting.
VPodDuo, which measures just 7.5 × 5 × 3.3 cm, transmitted results to a smartphone application through Bluetooth. The components cost US$62.63 per instrument when the researchers hand-assembled three units.
The study assessed analytical performance rather than clinical diagnostic accuracy. The researchers tested targets diluted in buffer, generally in triplicate, rather than patient specimens such as blood, saliva, or urine. Most assays also required separate heating equipment because the instrument did not contain a heating block.
Further studies using clinical specimens will be needed to evaluate sample preparation, reproducibility, calibration, and performance under varied environmental conditions. The findings support continued assessment of VPodDuo as a potential point-of-care complement to centralized molecular testing rather than a replacement for laboratory diagnostics.
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