A 128 × 1 SPAD-Camera for Protein Sequencing through Surface-Enhanced Raman Spectroscopy

Abstract

Nanopore sequencing through Surface-Enhanced Raman Spectroscopy (SERS) is a promising methodology to perform single-molecule analysis on nucleic acids and proteins, which relies on fast optical detectors with high sensitivity for spectral acquisition. To support this application, we developed a camera based on a 128 × 1 SPAD array, with custom microlenses to achieve 28% peak Photon Detection Efficiency (PDE). The camera supports high-speed readout at 1 MHz and features gating capabilities for fluorescence time filtering. Through translocation detection, the camera can trigger a molecule slow down mechanism, increasing the integration time for spectral acquisition. To further enhance signal collection and push gating performance to the sub-ns range, we designed a newer 128 × 4 chip in a 3D-stacked technology by STMicroelectronics. This new chip includes an innovative readout that can selectively capture only the spectral bands of interest, increasing readout frequency above 1 MHz.