publications

2025

1. HotMobile ’25

   

   VitalHide: Enabling Privacy-Aware Wireless Sensing of Vital Signs

   Yixuan Gao^*, Tanvir Ahmed^*, Zekun Chang, Thijs Roumen, and Rajalakshmi Nandakumar

   In Proceedings of the 26th International Workshop on Mobile Computing Systems and Applications (HotMobile ’25), 2025

   📍 Presented at NYC Privacy Day at Google (Fall 2024) • 🌟 Showcase: Kudos Publication Reader
   *Equal contribution

   Abs DOI Bib HTML

   Wireless sensing of vital signs offers promising opportunities for continuous health monitoring, but raises significant privacy concerns as sensitive biometric data can be inferred from RF signals. VitalHide addresses this challenge by developing privacy-preserving techniques that enable vital sign monitoring while protecting user privacy. Our approach uses differential privacy and secure computation methods to obscure individual measurements while maintaining clinical utility.

   @inproceedings{gao2025vitalhide,
     title = {VitalHide: Enabling Privacy-Aware Wireless Sensing of Vital Signs},
     author = {Gao, Yixuan and Ahmed, Tanvir and Chang, Zekun and Roumen, Thijs and Nandakumar, Rajalakshmi},
     booktitle = {Proceedings of the 26th International Workshop on Mobile Computing Systems and Applications (HotMobile '25)},
     pages = {37--42},
     year = {2025},
     publisher = {Association for Computing Machinery},
     address = {New York, NY, USA},
     doi = {10.1145/3708468.3711880},
     url = {https://dl.acm.org/doi/10.1145/3708468.3711880},
     note = {📍 Presented at <a href="https://rsvp.withgoogle.com/events/nyc-privacy-day-at-google-fall-2024" target="_blank">NYC Privacy Day at Google (Fall 2024)</a> • 🌟 Showcase: <a href="https://www.growkudos.com/publications/10.1145%252F3708468.3711880/reader" target="_blank">Kudos Publication Reader</a><br><strong>*Equal contribution</strong>},
   }

2. SCF ’25

   

   OriStitch: A Machine Embroidery Workflow to Turn Existing Fabrics into Self-Folding 3D Textiles

   Zekun Chang, Yixuan Gao, Yuta Noma, Shuo Feng, Xinyi Yang, Kazuhiro Shinoda, Tung D Ta, Koji Yatani, Tomoyuki Yokota, Takao Someya, Yoshihiro Kawahara, and others

   In Proceedings of the 10th annual ACM Symposium on Computational Fabrication (SCF ’25), 2025

   Abs DOI Bib HTML

   Traditional textiles are limited to 2D forms, but emerging applications require 3D textile structures. OriStitch introduces a novel machine embroidery workflow that transforms flat fabrics into self-folding 3D textiles using programmable stitching patterns. Our approach combines origami principles with computational fabrication to create complex 3D forms from conventional fabrics without additional materials or external actuators.

   @inproceedings{chang2025oristitch,
     title = {OriStitch: A Machine Embroidery Workflow to Turn Existing Fabrics into Self-Folding 3D Textiles},
     author = {Chang, Zekun and Gao, Yixuan and Noma, Yuta and Feng, Shuo and Yang, Xinyi and Shinoda, Kazuhiro and Ta, Tung D and Yatani, Koji and Yokota, Tomoyuki and Someya, Takao and Kawahara, Yoshihiro and others},
     booktitle = {Proceedings of the 10th annual ACM Symposium on Computational Fabrication (SCF '25)},
     pages = {1--12},
     year = {2025},
     publisher = {Association for Computing Machinery},
     address = {New York, NY, USA},
     doi = {10.1145/3641549.3652574},
     url = {https://zekunchang.com/portfolio/oristitch/},
   }

3. IASA ’25

   

   Assembly Stethoscope: Detecting Assembly Errors through Frequency Sweeping-A Feasibility Study

   Bo Liu, Yixuan Gao, Yin Li, Rajalakshmi Nandakumar, and Thijs Roumen

   In Proceedings of the 3rd ACM International Workshop on Intelligent Acoustic Systems and Applications (IASA ’25), Hong Kong, China, 2025

   Abs DOI Bib

   Manufacturing assembly processes often involve complex mechanical operations where errors can be costly and difficult to detect. Assembly Stethoscope presents a novel acoustic sensing approach that uses frequency sweeping techniques to identify assembly errors in real-time. Our feasibility study demonstrates how acoustic signatures can reveal improper connections, missing components, and other assembly defects across various manufacturing scenarios.

   @inproceedings{bo2025Stethoscope,
     author = {Liu, Bo and Gao, Yixuan and Li, Yin and Nandakumar, Rajalakshmi and Roumen, Thijs},
     title = {Assembly Stethoscope: Detecting Assembly Errors through Frequency Sweeping-A Feasibility Study},
     booktitle = {Proceedings of the 3rd ACM International Workshop on Intelligent Acoustic Systems and Applications (IASA '25)},
     pages = {19--24},
     numpages = {6},
     year = {2025},
     publisher = {Association for Computing Machinery},
     address = {New York, NY, USA},
     location = {Hong Kong, China},
     doi = {10.1145/3737901.3768368},
   }

4. arXiv

   

   SoilSound: Smartphone-based Soil Moisture Estimation

   Yixuan Gao, Tanvir Ahmed, Shuang He, Zhongqi Cheng, and Rajalakshmi Nandakumar

   arXiv preprint arXiv:2509.09823, 2025

   📋 Under review at ACM MobiCom 2026

   Abs Bib HTML

   Soil moisture monitoring is crucial for precision agriculture and environmental monitoring, but current methods require expensive specialized equipment. SoilSound introduces a novel smartphone-based approach that uses acoustic sensing to estimate soil moisture levels. By analyzing how sound propagation changes in different soil conditions, our method enables low-cost, accessible soil moisture measurement using commodity smartphone hardware.

   @article{gao2025soilsound,
     title = {SoilSound: Smartphone-based Soil Moisture Estimation},
     author = {Gao, Yixuan and Ahmed, Tanvir and He, Shuang and Cheng, Zhongqi and Nandakumar, Rajalakshmi},
     journal = {arXiv preprint arXiv:2509.09823},
     year = {2025},
     eprint = {2509.09823},
     archiveprefix = {arXiv},
     primaryclass = {cs.HC},
     url = {https://arxiv.org/abs/2509.09823},
     note = {📋 Under review at ACM MobiCom 2026},
   }

2024

1. EWSN ’24

   

   Feasibility of Radio Frequency Based Wireless Sensing of Lead Contamination in Soil

   Yixuan Gao, Tanvir Ahmed, Mikhail Mohammed, Zhongqi Cheng, and Rajalakshmi Nandakumar

   In Proceedings of the 21st International Conference on Embedded Wireless Systems and Networks (EWSN ’24), 2024

   🏆 Best Paper Award
   
   Media Coverage: Cornell Chronicle • Karmactive • phys.org • MSN • American Technion Society • X@CornellGrad • Slashdot

   Abs Bib HTML

   Lead contamination in soil poses significant health risks, particularly in urban environments and agricultural areas. Traditional soil testing methods are expensive and time-consuming, limiting widespread monitoring. This paper explores the feasibility of using radio frequency (RF) based wireless sensing techniques to detect lead contamination levels in soil samples. We develop a novel sensing approach that leverages the electromagnetic properties of lead-contaminated soil and demonstrate its effectiveness across various soil types and contamination levels.

   @inproceedings{gao2024soil,
     title = {Feasibility of Radio Frequency Based Wireless Sensing of Lead Contamination in Soil},
     author = {Gao, Yixuan and Ahmed, Tanvir and Mohammed, Mikhail and Cheng, Zhongqi and Nandakumar, Rajalakshmi},
     booktitle = {Proceedings of the 21st International Conference on Embedded Wireless Systems and Networks (EWSN '24)},
     pages = {99--104},
     year = {2024},
     publisher = {Junction Publishing},
     address = {Abu Dhabi, UAE},
     url = {https://ewsn.org/file-repository/ewsn2024/ewsn24-final99.pdf},
     note = {🏆 Best Paper Award <br><br> Media Coverage: <a href="https://news.cornell.edu/stories/2025/01/new-devices-radio-waves-reveal-lead-contamination-soil" target="_blank">Cornell Chronicle</a> • <a href="https://www.karmactive.com/soilscanner-affordable-device-detects-lead-in-urban-gardens/" target="_blank">Karmactive</a> • <a href="https://phys.org/news/2025-01-device-radio-reveal-contamination-soil.html" target="_blank">phys.org</a> • <a href="https://www.msn.com/en-us/news/technology/new-device-s-radio-waves-reveal-lead-contamination-in-soil/ar-AA1wRqyO" target="_blank">MSN</a> • <a href="https://ats.org/ats-news/new-devices-radio-waves-reveal-lead-contamination-soil/" target="_blank">American Technion Society</a> • <a href="https://x.com/CornellGrad/status/1878804461096722744" target="_blank">X@CornellGrad</a> • <a href="https://science.slashdot.org/story/25/01/04/0044250/new-devices-radio-waves-reveal-lead-contamination-in-soil" target="_blank">Slashdot</a>},
     dimensions = {true},
   }

2022

1. JMIR Biomed Eng

   

   Equity-Driven Sensing System for Measuring Skin Tone–Calibrated Peripheral Blood Oxygen Saturation (OptoBeat): Development, Design, and Evaluation Study

   Alexander T Adams, Ilan Mandel, Yixuan Gao, Bryan W Heckman, Rajalakshmi Nandakumar, and Tanzeem Choudhury

   JMIR Biomedical Engineering, 2022

   Abs DOI Bib HTML

   Background: Pulse oximetry is a noninvasive method for monitoring blood oxygen saturation that is essential for clinical care. However, existing devices exhibit systematic biases against patients with darker skin tones, leading to healthcare disparities. Objective: We aimed to develop an equity-driven sensing system for measuring skin tone-calibrated peripheral blood oxygen saturation. Methods: We developed OptoBeat, a novel pulse oximetry system that incorporates skin tone measurement and calibration algorithms to provide more accurate oxygen saturation readings across all skin tones. Results: Our evaluation shows improved accuracy and reduced bias across diverse skin tones compared to conventional pulse oximeters. Conclusions: OptoBeat represents a significant step toward more equitable medical sensing technology.

   @article{adams2022equity,
     title = {Equity-Driven Sensing System for Measuring Skin Tone--Calibrated Peripheral Blood Oxygen Saturation (OptoBeat): Development, Design, and Evaluation Study},
     author = {Adams, Alexander T and Mandel, Ilan and Gao, Yixuan and Heckman, Bryan W and Nandakumar, Rajalakshmi and Choudhury, Tanzeem},
     journal = {JMIR Biomedical Engineering},
     volume = {7},
     number = {1},
     pages = {e34934},
     year = {2022},
     publisher = {JMIR Publications Inc., Toronto, Canada},
     doi = {10.2196/34934},
     url = {https://biomedeng.jmir.org/2022/1/e34934/},
     dimensions = {true},
   }

2018

1. Poster: MobiCom ’18

   

   Analyzing Bitrates in Modern Wi-Fi Networks

   Yixuan Gao, Ali Abedi, Tim Brecht, and Ramya Bhagavatula

   In Proceedings of the 24th Annual International Conference on Mobile Computing and Networking (MobiCom’18), 2018

   Abs DOI Bib HTML

   Modern Wi-Fi networks support multiple transmission rates through adaptive rate selection algorithms. Understanding bitrate selection patterns is crucial for optimizing network performance. This poster presents an analysis of bitrate utilization patterns in contemporary Wi-Fi deployments, examining how different factors influence rate adaptation decisions and network throughput.

   @inproceedings{gao2018analyzing,
     title = {Analyzing Bitrates in Modern Wi-Fi Networks},
     author = {Gao, Yixuan and Abedi, Ali and Brecht, Tim and Bhagavatula, Ramya},
     booktitle = {Proceedings of the 24th Annual International Conference on Mobile Computing and Networking (MobiCom'18)},
     pages = {717--719},
     year = {2018},
     address = {New Delhi, India},
     publisher = {Association for Computing Machinery},
     doi = {10.1145/3241539.3267774},
     url = {https://dl.acm.org/doi/10.1145/3241539.3267774},
   }