Table of Contents
Journal of Thermodynamics
Volume 2016, Article ID 4932710, 8 pages
Research Article

Measuring Entropy Change in a Human Physiological System

1School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
2Department of Family & Preventive Medicine, University of Utah, Salt Lake City, UT 84108, USA
3Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84108, USA

Received 11 November 2015; Revised 2 January 2016; Accepted 4 January 2016

Academic Editor: Felix Sharipov

Copyright © 2016 Satish Boregowda et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The paper presents a novel approach involving the use of Maxwell relations to combine multiple physiological measures to provide a measure of entropy change. The physiological measures included blood pressure (BP), heart rate (HR), skin temperature (ST), electromyogram (EMG), and electrodermal response (EDR). The multiple time-series physiological data were collected from eight subjects in an experimental pilot study conducted at the Human Engineering Laboratory of NASA Langley Research Center. The methodology included data collection during a relaxation period of eighteen minutes followed by a sixty-minute cognitive task. Two types of entropy change were computed: (a) entropy change () due to blood pressure, heart rate, and skin temperature and (b) entropy change () due to electromyogram, electrodermal response, and skin temperature. The results demonstrate that entropy change provides a valuable composite measure of individual physiological response to various stressors that could be valuable in the areas of medical research, diagnosis, and clinical practice.