Arvind Pillai

I am a Student Researcher at Google and a 4th year PhD student at Dartmouth College, advised by Prof. Andrew Campbell. Previously, I was a research intern at Nokia Bell Labs (Cambridge, UK) (Summer 2024), and an AI & Data Graduate Scientist at AstraZeneca (2019-2021).

My interdisciplinary research centers on developing machine learning techniques to study health in real-world settings, utilizing data from wearable devices and mobile phone sensors. In particular, I am interested in these areas:

Health Foundation Models: Developing models that can generalize to many tasks is crucial for healthcare. To this end, I have developed PaPaGei, which is the first open-source foundation model for Photoplethysmography (PPG) [ICLR’25]; And proposed Time2Lang, which is a framework to integrate time-series foundation models with LLMs [CHIL’25].
Un/Semi-supervised Learning: I developed a method to detect rare life events from multi-modal sensing data [CHIL’23]. Additionally, I have also proposed a domain adaptation method and investigated the generalization of speech-based suicidal ideation detection [UbiComp’24a].
Behavior Modelling using Mobile Systems: I develop machine learning models and contribute to mobile systems targeted at understanding mental health. In this area, I have developed models for depression detection from in-the-wild smartphone images [CHI’24], an intervention system for improving social interactions in individuals with schizophrenia [IEEE PerCom Magazine’24], and maintain large-scale datasets with over 3 years of continuous sensing data [UbiComp’24b].

news

Jun, 2025	Excited to share that I’m starting my Student Researcher position at Google in Cambridge, MA! If you’re in the area, I’d love to grab coffee.
Apr, 2025	Delighted to share that Time2Lang is accepted to CHIL’25!
Jan, 2025	PaPaGei is accepted to ICLR 2025!
Dec, 2024	PaPaGei wins the Best Paper Award at the Time Series in the Age of Large Models workshop at NeurIPS 2024.
Oct, 2024	PaPaGei, a foundation model for PPG data is now available! Paper, Models, and Code
Oct, 2024	Presented “Investigating Generalizability of Speech-Based Suicidal Ideation Detection Using Mobile Phones” @ Ubicomp 2024
Jun, 2024	I will be interning at Nokia Bell Labs in Cambridge, UK for Summer 2024
May, 2024	Presented our work MoodCapture at CHI 2024 in Honolulu

Selected Publications

CHIL

Time2Lang: Bridging Time-Series Foundation Models and Large Language Models for Health Sensing Beyond Prompting

Arvind Pillai, Dimitris Spathis, Subigya Nepal, and 6 more authors

Conference on Health, Inference, and Learning, 2025

Bib PDF Code

@article{pillai2025beyond,
  title = {Time2Lang: Bridging Time-Series Foundation Models and Large Language Models for Health Sensing Beyond Prompting},
  author = {Pillai, Arvind and Spathis, Dimitris and Nepal, Subigya and Collins, Amanda C and Mackin, Daniel M and Heinz, Michael V and Griffin, Tess Z and Jacobson, Nicholas C and Campbell, Andrew},
  journal = {Conference on Health, Inference, and Learning},
  pages = {1--21},
  year = {2025},
  organization = {PMLR},
}

ICLR

PaPaGei: Open Foundation Models for Optical Physiological Signals

Arvind Pillai, Dimitris Spathis, Fahim Kawsar, and 1 more author

In International Conference on Learning Representations, 2025

Awareded Bib PDF Video Code

Best Paper Award at the NeurIPS Time Series in the Age Large Models Workshop

@article{pillai2024papagei,
  title = {PaPaGei: Open Foundation Models for Optical Physiological Signals},
  author = {Pillai, Arvind and Spathis, Dimitris and Kawsar, Fahim and Malekzadeh, Mohammad},
  journal = {In International Conference on Learning Representations},
  year = {2025},
  models = {https://zenodo.org/records/13983110},
  selected = true,
}

CHI

MoodCapture: Depression Detection Using In-the-Wild Smartphone Images

Subigya Nepal*, Arvind Pillai*, Weichen Wang, and 8 more authors

In Proceedings of the CHI Conference on Human Factors in Computing Systems , 2024

Bib PDF Video

@inproceedings{nepal2024moodcapture,
  title = {MoodCapture: Depression Detection Using In-the-Wild Smartphone Images},
  author = {Nepal*, Subigya and Pillai*, Arvind and Wang, Weichen and Griffin, Tess and Collins, Amanda C and Heinz, Michael and Lekkas, Damien and Mirjafari, Shayan and Nemesure, Matthew and Price, George and others},
  booktitle = {Proceedings of the CHI Conference on Human Factors in Computing Systems},
  pages = {1--18},
  year = {2024},
}

UbiComp

Investigating Generalizability of Speech-based Suicidal Ideation Detection Using Mobile Phones

Arvind Pillai, Subigya Kumar Nepal, Weichen Wang, and 8 more authors

Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies, 2024

Bib PDF

@article{pillai2024investigating,
  title = {Investigating Generalizability of Speech-based Suicidal Ideation Detection Using Mobile Phones},
  author = {Pillai, Arvind and Nepal, Subigya Kumar and Wang, Weichen and Nemesure, Matthew and Heinz, Michael and Price, George and Lekkas, Damien and Collins, Amanda C and Griffin, Tess and Buck, Benjamin and others},
  journal = {Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies},
  volume = {7},
  number = {4},
  pages = {1--38},
  year = {2024},
  publisher = {ACM New York, NY, USA},
}