# Portable Dynamic Laser Speckle Imaging for Rapid Antimicrobial Susceptibility Testing

## TL;DR

A portable, low-cost device uses laser speckle imaging and a cellphone camera to rapidly test how bacteria respond to antibiotics, helping make faster treatment decisions.

## Contribution

A 3D-printed, portable AST device using dynamic laser speckle imaging and machine learning for rapid, low-cost antibiotic susceptibility testing.

## Key findings

- The pDLSI device achieved AST results within 2–3 hours for both Gram-positive and Gram-negative bacteria.
- The system uses spatiotemporal decorrelation maps and machine learning to determine minimum inhibitory concentrations.
- The device is compact, low-cost, and suitable for point-of-care use in resource-limited settings.

## Abstract

Antimicrobial resistance remains a pressing global health threat. Conventional antimicrobial susceptibility testing (AST) methods are limited by long incubation times and centralized laboratory requirements, hindering timely decision-making in resource-limited settings. This study introduces a 3D printed, portable dynamic laser speckle imaging (pDLSI) device for rapid AST. This device has a 10 × 3 × 3 cm3 footprint, equipped with a low-cost laser diode, a lens assembly, and a cuvette sample holder. Speckle fluctuations induced by bacterial activity are captured on a cellphone camera, visualized using spatiotemporal decorrelation maps, and analyzed using machine learning to determine minimum inhibitory concentrations within 2–3 h. To demonstrate the performance, we studied two representative Gram-positive and Gram-negative bacterial strains (Enterococcus faecalis and Escherichia coli), along with two antibiotics (ampicillin and gentamicin). The simple construction, portability, and intuitive operation of the pDLSI system can potentially facilitate initial diagnostic decisions at the point of care.