Quantitative Point-of-Care Cadmium Detection Using a MEMS Spectrometer-Based LFA Reader

We present a portable sensor for quantitative detection of the critical heavy metal toxin, Cadmium (Cd), by LFA, replacing high Coefficient of Variation (CV) image-based analysis with a MEMS spectrometer. Fabricated via X-ray lithography, the spectral chip achieves a$200: 1$high aspect ratio (HAR) and 5 nm wavelength resolution at VIS∼NIR bandwidth. This direct spectroscopic system, over 75 % smaller than benchtop units, enhances total measurement precision to$13 \% \text{CV}$(including strip variability), while the instrument's standalone CV is under 3 %. The sensor achieved a 2.75 ppb Limit of Detection (LOD) with a calibration curve$R^{2}$of 0.966 across a$4 \sim 56 p p b$range.