Noninvasive measurement of membrane potential modulation in microorganisms: Photosynthesis in green algae

Eun Hee Lee, Seung Woo Lee, Ravi F. Saraf

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Cell membrane potential (CMP) modulation is a physical measurement to quantitatively probe cell physiology in real time at high specificity. Electrochemical field effect transistors (eFETs) made from graphene and Si nanowire provide strong mechanical and electrical coupling with neurons and muscle cells to noninvasively measure CMP at high sensitivity. To date, there are no noninvasive methods to study electrophysiology of microorganisms because of stiff cell walls and significantly smaller membrane polarizations. An eFET made from the smallest possible nanostructure, a nanoparticle, with sensitivity to a single-electron charge is developed to noninvasively measure CMP modulation in algae. The applicability of the device is demonstrated by measuring CMP modulation due to a light-induced proton gradient inside the chloroplast during photosynthesis. The ∼9 mV modulation in CMP in algae is consistent with the absorbance spectrum of chlorophyll, photosynthetic pathway, and inorganic carbon source concentration in the environment. The method can potentially become a routine method to noninvasively study electrophysiology of cells, such as microorganisms for biofuels.

Original languageEnglish (US)
Pages (from-to)780-786
Number of pages7
JournalACS Nano
Issue number1
StatePublished - Jan 28 2014


  • cell membrane potential
  • electrochemical transistor
  • nanoparticle array
  • photosynthesis
  • single electron transistor

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy


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