Thermal conductivity of a Jurkat cell measured by a transient laser point heating method


Thermal conduction is the transport of energy due to random molecular motion across a temperature gradient. This property is vital as it governs every heat transfer problem in engineering and basic science research. As such, there has been rapid development of technology particularly with a focus on heat transfer in nanostructures, wires, and macromolecules. For instance, for one to understand a biological reaction in living cells and transport of thermal energy in biological systems, measurement of temperature and thermal properties is important. Previous research in the field reveals that thermal characterization of cells is vital to obtain critical knowledge for screening, diagnostics, basic and clinical science, and the pharmaceutical industry. At present, there are several thermal-analysis techniques available for measuring the thermodynamic and thermophysical properties of biological samples. However, temperature change within the cells is usually small. Moreover, such temperature change is transient due to the thermo-influence by the extracellular environment, making temperature change difficult to measure using conventional temperature detection methods.

Some techniques incorporate a thermal couple (25μm) or sensor to improve efficiency.  However, the accuracy of such technique is questionable due to the sensor size. Specifically, measurement of transient temperature remains to be confirmed for the development of micro-thermocouple sensors of size 2μm to 20μm. Consequently, a much more precise and faster-response technique is required to measure intracellular transient temperature changes in real-time. In this regard, University of North Texas researchers: Ramesh Shrestha (PhD), Rohini Atluri (PhD candidate), Professor Denise Perry Simmons, and Professor Tae-Youl Choi in collaboration with Professor Dongsik Kim at POSTECH in South Korea developed a novel technique that utilizes a laser point heat source for temporal temperature rise in a micro-pipette thermal sensor. Specifically, they proposed a technique that could characterize heat conduction of a measured sample, the Jurkat cell, thus measuring the sample’s thermal conductivity. Their work is currently published in the research journal, International Journal of Heat and Mass Transfer.

In their approach, the research team incorporated the computational model in COMSOL to solve for the transient temperature and used the multi-parameter fitting of the experimental data using MATLAB. To address the influence of a Jurkat cell’s chemical composition on thermal conductivity (TC), the researchers compared three structural models for prediction of effective TC in heterogeneous materials thereby determining the weight percentage of the Jurkat cell. Lastly, they validated the accuracy of the measurement technique, itself, by measuring polyethylene microspheres and observed 1% deviation from published data.

The authors reported that when considering water and protein as the major constituents, they found that a combination of Maxwell-Euken and Effective Medium Theory modeling provided the closest approximation to published weight percent data and, therefore, was recommended for prediction of the cell composition. Moreover, following their approach, thermal conductivity for the microsphere was determined to be 0.327 W/(mK) by the MPTS technique with reproducibility of 98% and accuracy with less than 1% error, in good agreement with the published data.

In summary, the study presented a new characterization technique for measuring the thermal properties of a single biological cell. The study further demonstrated the validity of the MPTS technique in measuring the spherical microparticles by measuring industry standard polyethylene microspheres. Remarkably, the presented technique was reported to be mechanically non-invasive for characterization of thermal conductivity of microscale materials. In a statement to Advances in Engineering, Professor Tae-Youl Choi explained their developed thermal conductivity measurement using the MPTS is a unique technique for the characterization of thermal properties and temperature measurement of microspheres and single biological cells. This work was supported by National Science Foundation (award number: 1906553).

Thermal conductivity of a Jurkat cell measured by a transient laser point heating method - Advances in Engineering

About the author

Dr. Tae-Youl Choi is a Professor and a Lab Head of Laboratory of Small Scale Instrumentation in the Department of Mechanical Engineering at UNT. Choi group has established three main research thrusts where his main research interest is based on thermal and fluid science and engineering at micro and nanoscale. One thrust is cellular level thermal characterization to understand the pathogenesis of the disease and translational implications. Choi group apply principles of materials science to human cells, considering “the cell as a material” combined with the biological sciences such as the cell cycle. To this end, Choi group has focused on thermal modeling and numerical simulation using COMSOL and Matlab. The second thrust is focused on wave-matter interaction. Choi utilized femtosecond laser for microscale and nanoscale manufacturing. He also conducted Multiphysics simulation using the finite-domain time-difference method to elucidate the near field enhancement effect and consequent energy transfer mechanisms during AFM-assisted nanomachining.

Recently Dr. Choi has been involved with an NSF-supported EFRI project where a sound wave was used for the investigation of non-reciprocal metamaterials that arise in periodic media. The so-called phonoic crystal structures have been invented for the design of tunable lens, filters, and acoustic diodes. The last thrust is on utilization and characterization of nanosystems where fundamental properties of nanoscale systems can be found to apply them for various energy applications. Dr. Choi earned his PhD degree from University of California, Berkeley. His BS and MS degree are from Seoul National University.

About the author

Denise Perry Simmons is a Biomedical Researcher whose career as Director John Theurer Cancer Ctr Clinical Research and University of North Texas AVP R&D/Sr. Director STEM has been influenced by early research experiences. The portfolio assembles at the leading-edge of pioneering work with University of Chicago Molecular Biologist H. Guy Williams Ashman, Ph.D.-endocrinology, Rush Presbyterian St. Luke Immunologist Henry Gewurz, M.D. – C-reactive Protein, Baylor College of Medicine Bert O’Malley, M.D., Susan H. Socher, Ph.D. – gene operon/MMTV, University of Chicago Molecular Geneticist Bernard Roizman, Sc.D. – HSV-1,-2, Rockefeller University Nobel Laureate Gerald Edelman, M.D.- hybridoma technology, University of Arizona Medicinal Chemist, Laurence H. Hurley, Ph.D. -DNA G-Quadruplex. Her education and training profile: Ph.D. Biological Sciences UT Austin and UT MD Anderson; Postdoctoral Fellow Medicinal Chemistry. UT Austin College of Pharmacy, Fellow NIH-National Cancer Institute Dr. Simmons publications reflect broad expertise and biomedical impact captured in Carcinogenesis, J Virol, J Nutr Immunol, J Immunol, Clin Chem, Ann Neurol, Nanomaterials, J Applied Physics, Human Genome Variation Database. She is the recipient of numerous patents, appointments and awards including Immunoassay Screens, National Patient Advocacy Think Tank- Health Disparities Robert Wood Johnson, New Jersey Commission on Cancer Research, Cancer Alliance of Texas, the American Association of Cancer Research Minority Scholar Award, and the National Institutes of Health- National Cancer Institute Technology Transfer Award.

Her work spans the transdisciplinary spectrum to affect translational outcomes. She focuses on leveraging the notion of the “cell as a material”. Dr. Simmons’ research continues to inform cell life cycle transition from normal to diseased at the intersections of discovery in materials science and engineering, technology, physical and biological sciences.

About the author

Professor Dongsik Kim received his Ph. D. degree from UC Berkeley (USA) in 1998. After serving as an Assistant Professor in the Mechanical Eng. Department at UT Austin (USA) for two years, he joined Pohang University of Science and Technology (POSTECH, Republic of Korea) in 2000 and is currently a professor in the Mechanical Engineering Department. His main research interests lie in laser materials processing and microscale thermal sensors/systems, with emphasis on metal 3D printing, surface cleaning/modification, micro-thermal sensors, and modeling and simulation of laser interaction with materials. He published numerous archival journal papers and won several awards, including the inaugural Kwangwon Award from KSLP and the Netzsch KSTP Thermophysical Properties Award.

About the author

Dr. Ramesh Shrestha was a PhD student under supervision of Dr. Tae-Youl Choi. He earned his Doctoral degree in 2020 from Department of Mechanical Engineering at UNT. He is now a research associate in Dr. Choi’s research group. His research interest is in thermal characterization of thermal fluids, micro-nano materials, thin films, and biological cells using micro-pipette thermal sensor and laser point heating. He has developed the numerical model for the experiment using COMSOL simulation and MATLAB Simulink in addition to micropipette-based thermal sensor system.

About the author

Ms. Rohini Atluri is a PhD student at the Mechanical Engineering Department of University of North Texas. Her research is focused on thermal characterization of cancer cells, specifically, glioblastoma multiforme (GBM; brain cancer) and epithelial ovarian cancer (EOC). Research interests also include developing 3D spheroid models representing tumor, to identify the boundaries between normal and cancer cells based on thermal properties of the cells and combination treatment for GBM using Silver nanoparticles and low-level laser.


R. Shrestha, R. Atluri, D.P. Simmons, D.S. Kim, T.Y. Choi. Thermal conductivity of a Jurkat cell measured by a transient laser point heating method. International Journal of Heat and Mass Transfer: volume 160 (2020) 120161.

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