A low-cost, high-sensitivity WSPRi system using a multi-LED array and smoothness-constrained reconstruction algorithm

Conventional wavelength-modulated surface plasmon resonance imaging (WSPRi) systems rely on costly spectrometers or tunable filters, limiting their accessibility. We report a low-cost, high-performance WSPRi system that replaces these components with an array of six monochromatic LEDs. A Smoothness-Constrained Reconstruction algorithm accurately reconstructs SPR spectra from the LED data, effectively suppressing noise and avoiding spectral broadening. Our system achieves a refractive index resolution of 1.65×10−6 RIU, and we demonstrate its high-throughput capability with a parallel immunoassay. This work provides a robust and cost-effective platform that makes high-sensitivity SPR sensing viable for broader applications.