Ph.D. student, RA
I’m a senior PhD student and my research interests include signal processing for robustness, sensor design, statistical analysis and machine learning, especially for the application domain of wearable physiological sensors. On this page you will find links to more information about me as well as some projects I’ve worked on.
I received my Bachelor’s and Master’s degrees in Computer Engineering from the University of Texas at Dallas in May 2012 and May 2015 respectively. I am currently a Ph.D. student in Computer Engineering and a member of the ESP Lab at Texas A&M University. In my spare time I enjoy watching football (soccer), am a huge movie buff and love traveling. My love for statistical analysis at work very often bleeds into collecting stats and making charts/graphs for all these hobbies as well! I also enjoy writing, which has served me well for research papers, although my extended family probably resent my long essays about football. I have industry experience with two summer internships and am actively seeking a full-time position upon my anticipated graduation in Spring 2018.
Google Scholar: https://scholar.google.com/citations?user=-gVAafMAAAAJ
I was part of the development of ‘BioWatch’, a wrist-worn device that can measure PPG and ECG simultaneously to estimate heart rate and blood oxygenation. More importantly, it can measure pulse transit time, which is correlated with blood pressure. I was involved in high level system design, firmware development, experimental testing on human subjects as well as data analysis. Here is a link for more info as well as a video of the BioWatch in action.
Texas Instruments Reference Designs
I was involved in the development of reference designs for cutting-edge analog front-ends developed by Texas Instruments (TI). This included a suite of health monitoring devices for measuring physiological parameters including body fat %, heart rate, blood oxygenation, step count and ECG. I was responsible for firmware development on the MSP430 microcontroller including on-board signal processing and communication of data. I was also involved in system design and testing. This ecosystem of devices and integrated app called HealthHub were presented at CES 2013.
Brain Computer Interface
I was involved in the development of a mobile, wearable EEG acquisition system, with one of the applications being brain computer interface (BCI). I was involved in firmware development and system design. I did extensive research looking into the factors that determine electrode scalp contact quality, and developed custom electrodes to counteract the effects of bad contact. I also oversaw several experimental data collections on human subjects to validate the system.
Signal Processing for Motion Artifacts
One of the key challenges for wearable physiological sensors is motion artifacts, as the user goes about their daily activities or exercise routines. As part of my research I developed a statistical signal processing framework based on particle filtering to track heart rate from cardiac signals affected by motion artifacts. The developed techniques were validated on real ECG and PPG data from human subjects running on a treadmill, with an average error in heart rate estimation < 2bpm.
J4) Viswam Nathan, Roozbeh Jafari, “Particle Filtering and Sensor Fusion for Robust Heart Rate Monitoring using Wearable Sensors”, IEEE J-BHI, accepted for publication.
J3) Viswam Nathan, Roozbeh Jafari, “Design Principles and Dynamic Front End Reconfiguration for Low Noise EEG Acquisition with Finger Based Dry Electrodes”, IEEE T-BioCAS, vol. 9, no. 5, pp. 631-640, October 2015.
J2) Simi Susan Thomas, Viswam Nathan, Chengzhi Zong, Karthikeyan Soundarapandian, Xiangrong Shi, Roozbeh Jafari, “BioWatch: A Non-invasive Wrist-based Blood Pressure Monitor that Incorporates Training Techniques for Posture and Subject Variability”, IEEE J-BHI, vol.20, no.5, pp. 1291-1300, September 2016.
J1) Yuan Zou, Viswam Nathan, Roozbeh Jafari, “Automatic Identification of Artifact-related Independent Components for Artifact Removal in EEG Recordings”, IEEE J-BHI, vol.20, no.1, pp. 73-81, January 2016.
C10) Bassem Ibrahim, Viswam Nathan, Roozbeh Jafari, “Exploration and Validation of Alternate Sensing Methods for Wearable Continuous Pulse Transit Time Measurement Using Optical and Bioimpedance Modalities”, IEEE EMBC, Jul 11-15, 2017, Jeju Island, South Korea.
C9) Zachary Trujillo, Viswam Nathan, Gerard L. Coté, Roozbeh Jafari, “Design and Parametric Analysis of a Wearable Dual-Photoplethysmograph Based System for Pulse Wave Velocity Detection”, IEEE ISCAS, May 28-31, 2017, Baltimore, MD
C8) Qingxue Zhang, Chakameh Zahed, Viswam Nathan, Drew A. Hall, Roozbeh Jafari, “An ECG Dataset Representing Real-World Signal Characteristics for Wearable Computers”, IEEE BioCAS, October 22-24, 2015, Atlanta, GA
C7) Viswam Nathan, Ilge Akkaya, Roozbeh Jafari, “A Particle Filter Framework for the Estimation of Heart Rate from ECG Signals Corrupted by Motion Artifacts”, IEEE EMBC, August 25-29, 2015, Milan, Italy.
C6) Viswam Nathan, Roozbeh Jafari, “Reducing the Noise Level of EEG Signal Acquisition through Reconfiguration of Dry Contact Electrodes”, IEEE BioCAS, October 22-24, 2014, Lausanne, Switzerland.
C5) Viswam Nathan, Roozbeh Jafari, “Characterizing Contact Impedance, Signal Quality and Robustness as a Function of the Cardinality and Arrangement of Fingers on Dry Contact EEG Electrodes”, IEEE EMBC, Aug 26-30, 2014, Chicago, IL.
C4) Simi Susan Thomas, Viswam Nathan, Chengzhi Zong, Ebunoluwa Akinbola, Praveen Aroul, Lijoy Philipose, Karthikeyan Soundarapandian, Xiangrong Shi, Roozbeh Jafari, “BioWatch – A Wrist Watch based Signal Acquisition System for Physiological Signals including Blood Pressure”, IEEE EMBC, Aug 26-30, 2014, Chicago, IL.
C3) Omid Dehzangi, Viswam Nathan, Chengzhi Zong, Chang Won Lee, Insoo Kim, Roozbeh Jafari, “A Novel Stimulation for Multi-Class SSVEP-Based Brain-Computer Interface using Patterns of Time-Varying Frequencies”, IEEE EMBC, Aug 26-30, 2014, Chicago, IL.
C2) Roozbeh Jafari, Omid Dehzangi , Chengzhi Zong, Viswam Nathan, “BCIBench: A Benchmarking Suite for EEG-based Brain Computer Interface”, Optimizations for DSP and Embedded Systems (ODES-11), February 14-16, 2014, Orlando, FL.
C1) Yuan Zou, Omid Dehzangi, Viswam Nathan, Roozbeh Jafari, “Automatic Removal of EEG Artifacts Using Electrode-Scalp Impedance”, ICASSP, May 4-9, 2014, Florence, Italy.
BC1) Viswam Nathan, Simi Susan Thomas, Roozbeh Jafari, “Smart Watches for Physiological Monitoring: A Case Study on Blood Pressure Measurement”, pages 231–252. Springer International Publishing, Cham, 2017.
M1) Viswam Nathan, “Wearable brain computer interface are we there yet?”, Magazine XRDS: Crossroads, vol.20, no.2, pp. 56-60, ACM, 2013.
Demonstration and Workshop Papers:
WP2) Simi Susan Thomas, Viswam Nathan, Chengzhi Zong, Praveen Aroul, Lijoy Philipose, Karthikeyan Soundarapandian, Xiangrong Shi, Roozbeh Jafari, “BioWatch: A Wrist Watch based Physiological Signal Acquisition System”, ACM/IEEE IPSN, April 15-17, 2014, Berlin, Germany.
WP1) Viswam Nathan, Jian Wu, Chengzhi Zong, Yuan Zou, Omid Dehzangi, Mary Reagor, Roozbeh Jafari, “A 16-channel Bluetooth Enabled Wearable EEG Platform with Dry-contact Electrodes for Brain Computer Interface”, ACM International Conference on Wireless Health, November 1-3, 2013, Baltimore, MD.
Roozbeh Jafari, Viswam Nathan, Bassem Ibrahim “SYSTEM AND METHOD FOR CUFF-LESS BLOOD PRESSURE MONITORING,” set forth in a Provisional application for Letters Patent of the United States, already filed on July 7, 2017 as U.S. Application No. 62/529,944;