Testing a Drop of Liquid Using Smartphone LiDAR

TL;DR

This paper introduces a novel, accessible smartphone LiDAR-based system that measures fluid properties like viscosity and distinguishes between different liquids using speckle pattern analysis, enabling contactless testing with minimal sample volume.

Contribution

The first system to determine fluid properties using smartphone LiDAR sensors, enabling contactless, low-volume, and versatile liquid analysis without laboratory equipment.

Findings

Can distinguish between different fat contents in liquids.

Successfully identifies adulterated milk.

Differentiates coagulated from uncoagulated blood using a single drop.

Abstract

We present the first system to determine fluid properties using the LiDAR sensors present on modern smartphones. Traditional methods of measuring properties like viscosity require expensive laboratory equipment or a relatively large amount of fluid. In contrast, our smartphone-based method is accessible, contactless and works with just a single drop of liquid. Our design works by targeting a coherent LiDAR beam from the phone onto the liquid. Using the phone's camera, we capture the characteristic laser speckle pattern that is formed by the interference of light reflecting from light-scattering particles. By correlating the fluctuations in speckle intensity over time, we can characterize the Brownian motion within the liquid which is correlated with its viscosity. The speckle pattern can be captured on a range of phone cameras and does not require external magnifiers. Our results show that we can distinguish between different fat contents as well as identify adulterated milk. Further, algorithms can classify between ten different liquids using the smartphone LiDAR speckle patterns. Finally, we conducted a clinical study with whole blood samples across 30 patients showing that our approach can distinguish between coagulated and uncoagulated blood using a single drop of blood.