#### Event Title

The minimum electrical field that can be detected by a biological membrane—thermal noise limit

#### Description

Thermal electrical noise in living cells is considered as the minimum threshold for several biological response mechanisms that pertain to electric fields. Existing models that purport to explain and interpret this phenomena yield perplexing results. In the simplest model, the biomembrane is considered as a linear dielectric which yields an equilibrium noise level that is several orders of magnitude larger than that is observed experimentally. An alternative approach of estimating the thermal noise as the Nyquist noise of a resistor within a finite frequency bandwidth yields little physical insight. In this study, we argue that the nonlinear dielectric behavior must be accounted for. Using a statistical mechanics approach, we analyze the thermal fluctuations of a fully coupled electromechanical biomembrane. We establish the benchmark results for model fluid membranes and obtain physically reasonable estimates of the minimum electrical field threshold that can be detected by cells. Qualitatively, at least, our model is capable of predicting all known experimental results. The predictions of our model also suggest that further experimental work is warranted to clarify the inconsistencies in the literature.

#### Recommended Citation

Ahmadpoor, F.,
Sharma, P.,
&
Liu, L.
(2014).
The minimum electrical field that can be detected by a biological membrane—thermal noise limit.
In A. Bajaj, P. Zavattieri, M. Koslowski, & T. Siegmund (Eds.).
*
Proceedings of the Society of Engineering Science 51st Annual Technical Meeting, October 1-3, 2014
*,
West Lafayette: Purdue University Libraries Scholarly Publishing Services, 2014.
http://docs.lib.purdue.edu/ses2014/mfts/mvc/7

The minimum electrical field that can be detected by a biological membrane—thermal noise limit

Thermal electrical noise in living cells is considered as the minimum threshold for several biological response mechanisms that pertain to electric fields. Existing models that purport to explain and interpret this phenomena yield perplexing results. In the simplest model, the biomembrane is considered as a linear dielectric which yields an equilibrium noise level that is several orders of magnitude larger than that is observed experimentally. An alternative approach of estimating the thermal noise as the Nyquist noise of a resistor within a finite frequency bandwidth yields little physical insight. In this study, we argue that the nonlinear dielectric behavior must be accounted for. Using a statistical mechanics approach, we analyze the thermal fluctuations of a fully coupled electromechanical biomembrane. We establish the benchmark results for model fluid membranes and obtain physically reasonable estimates of the minimum electrical field threshold that can be detected by cells. Qualitatively, at least, our model is capable of predicting all known experimental results. The predictions of our model also suggest that further experimental work is warranted to clarify the inconsistencies in the literature.