A MEMS Photosynthetic Electrochemical Cell Powered by Subcellular Plant Photosystems

Abstract

A microelectromechanical systems (MEMS) photosynthetic electrochemical cell <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(mu PEC)$</tex> was demonstrated that harnesses the subcellular thylakoid photosystems isolated from spinach cells to convert light energy into electricity. Subject to light intensity of 2000 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$mu mol$</tex> photons/ <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$ m ^2$</tex> /s, it generated an open circuit voltage (OCV) of 470 mV and a current density of 1.1 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$mu A/cm^2$</tex> at 5.2 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$mu V$</tex> . In the dark, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$mu PEC$</tex> continued to yield power for a few minutes using reduced equivalents generated during illumination, generating 330 mV OCV and 0.1 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$mu A/cm^2$</tex> with a 1 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$ kOmega$</tex> load. The output level is comparable to other MEMS biological fuel cells previously reported. The biosolar cell was bulk-micromachined from silicon and Pyrex substrates and assembled like a fuel cell in an anode-PEM-cathode configuration. This biosolar cell could have potential to serve as a power source for micro-scale devices like remote sensors.1359