Miniature Fiber-Spectrophotometer for Real-Time Biomarkers Detection

This paper presents a miniature and cost-effective cell fiber-spectrophotometer based on fluorescence emission sensing for real-time detection of biomarkers. The prototype comprises a highly sensitive spectrometer embedded in an inexpensive 3D-printed housing and a custom-designed printed circuit board to transmit the data wirelessly. Results show that this portable system can identify micro-volume samples of tubulin protein, a well-known biomarker, to study different types of cancer. Additionally, our ambulatory prototype is small in size (30 mm
$\times24$
mm
$\times43$
mm), lightweight (19 g), economical, and low-power (103 mW). Fluorescence spectrophotometry measurement results obtained
in vitro
for stained VERO E6 cells using the presented prototype are reported. A set of samples with varying concentrations of Alexa Fluor 488 were also tested, and their spectral responses were measured within the range of 340–850 nm with a resolution of 15 nm. The measured limits of quantification and detection are 20 and
$4~\mu \text{g}$
/mL, respectively, while the measured responsivity is 85 mV/nW with a minimum detectable power of 117 fW at 519 nm. Intra- and inter-day relative standard deviations of 1.5% and 4.7%, respectively, were measured during longitudinal sensitivity experiments.