# Design of Functionalized Photon Sieves for the Detection of Biomarkers in Running Fluids

## TL;DR

Researchers designed a new optical sensor using photon sieves to detect human serum albumin in fluids, offering a compact and low-cost solution.

## Contribution

A novel functionalized photon sieve sensor for biomarker detection in running fluids is introduced.

## Key findings

- The sensor detects human serum albumin by measuring changes in spectral reflectance.
- The signal decreases to 0.43 of its initial value upon biomarker binding.
- Photon sieves show potential for compact, lightweight, and low-cost optical chemical sensors.

## Abstract

In this work, we present the design of a prototype fluid analyzer based on photon sieves, permeable diffractive optical elements capable of focusing light through diffraction. The photon sieve comprises a spatial distribution of circular apertures patterned onto an aluminum substrate, which provides intrinsic fluid permeability and functions as either a lens or a mirror. In our approach, the aluminum surface is chemically functionalized to detect a specific biomolecular marker—human serum albumin—whose interaction with the surface induces measurable changes in the spectral reflectance. The operating wavelength is selected to maximize the reflectance contrast produced by the presence of the biomarker. The optical set-up is configured such that the light source and detector lie in the same plane when the photon sieve operates in reflection. A combined geometrical and diffractive analysis is conducted to optimize their positions. Upon detection of the biomarker, the measured signal decreases to 0.43 of its initial value prior to biomarker binding. These results highlight photon sieves as a promising platform for the development of compact, lightweight, and low-cost optical chemical sensors for running fluids.