(615f) A Stomatal Electro-Mechanical Pore Size Sensor (SEMPSS) for Persistent Monitoring of Plant Physiology

Stomatal function can be used effectively to monitor plant hydraulic efficiency, photo-sensitivity and CO₂

conductance. Current approaches to measure stomatal aperture size, such as mold casting or fluorometric

techniques, do not allow real time or persistent monitoring of the stomata over the timescales relevant for plant

physiology including growth and maturation, or gradual changes in soil water potential associated with drought

conditions. Herein, we utilize a nanoparticle-based conducting ink that preserves stomatal function to print a

highly stable, electrical conductometric sensor actuated by the stomata pore itself, repeatedly and reversibly for

over 1 week. This Stomatal Electro-Mechanical Pore Size Sensor (SEMPSS) allows for real-time tracking of the

latency of stomatal opening and closing times, which we show vary from 7±0.5 to 25±0.5 min for the former and

from 53±0.5 to 45±0.5 min for the latter in Spathiphyllum. These values are shown to correlate with a drop in soil

water potential and the onset of the wilting response, in quantitative agreement with a mathematical model of

stomata signaling in function. A single stoma of Spathiphyllum is shown to distinguish between incident light

intensities (up to 12 mW/cm²) with temporal latency slow as 7±0.5 min. Over a seven day period, the latency in

opening and closing times are stable throughout the plant diurnal cycle and increase gradually with physiological

changes associated with drought onset. The monitoring of stomata function over relevant timescales for plant

physiology will improve understanding of plant adaptation to environmental factors.