LiquID: A wireless liquid identifier

Ashutosh Dhekne, Mahanth Gowda, Yixuan Zhao, Haitham Hassanieh, Romit Roy Choudhury

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Scopus citations

Abstract

This paper shows the feasibility of identifying liquids by shining ultra-wideband (UWB) wireless signals through them. The core opportunity arises from the fact that wireless signals experience distinct slow-down and attenuation when passing through a liquid, manifesting in the phase, strength, and propagation delay of the outgoing signal. While this intuition is simple, building a robust system entails numerous challenges, including (1) pico-second scale time of flight estimation, (2) coping with integer ambiguity due to phase wraps, (3) pollution from hardware noise and multipath, and (4) compensating for the liquid-container’s impact on the measurements. We address these challenges through multiple stages of signal processing without relying on any feature extraction or machine learning. Instead, we model the behavior of radio signals inside liquids (using principles of physics), and estimate the liquid’s permittivity, which in turn identifies the liquid. Experiments across 33 different liquids (spread over the whole permittivity spectrum) show median permittivity error of 9%. This implies that coke can be discriminated from diet coke or pepsi, whole milk from 2% milk, and distilled water from saline water. Our end system, LiquID, is cheap, non-invasive, and amenable to real-world applications.

Original languageEnglish (US)
Title of host publicationMobiSys 2018 - Proceedings of the 16th ACM International Conference on Mobile Systems, Applications, and Services
PublisherAssociation for Computing Machinery, Inc
Pages442-454
Number of pages13
ISBN (Electronic)9781450357203
DOIs
StatePublished - Jun 10 2018
Event16th ACM International Conference on Mobile Systems, Applications, and Services,MobiSys 2018 - Munich, Germany
Duration: Jun 10 2018Jun 15 2018

Publication series

NameMobiSys 2018 - Proceedings of the 16th ACM International Conference on Mobile Systems, Applications, and Services

Conference

Conference16th ACM International Conference on Mobile Systems, Applications, and Services,MobiSys 2018
CountryGermany
CityMunich
Period6/10/186/15/18

All Science Journal Classification (ASJC) codes

  • Information Systems
  • Software
  • Hardware and Architecture
  • Computer Networks and Communications

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  • Cite this

    Dhekne, A., Gowda, M., Zhao, Y., Hassanieh, H., & Choudhury, R. R. (2018). LiquID: A wireless liquid identifier. In MobiSys 2018 - Proceedings of the 16th ACM International Conference on Mobile Systems, Applications, and Services (pp. 442-454). (MobiSys 2018 - Proceedings of the 16th ACM International Conference on Mobile Systems, Applications, and Services). Association for Computing Machinery, Inc. https://doi.org/10.1145/3210240.3210345