Cornell University

Alan N Lakso

Abraham D Stroock

Vinay Pagay

Bojan Robert Ilic

David Sessoms

Meredith Metzler

Michael Santiago

A multimodal sensor includes a microtensiometer for measuring the chemical potential of a sub-saturated liquid, a temperature sensor, and a water content sensor. The microtensiometer includes a sensor body comprising a first gas-impermeable layer, an opposing second gas-impermeable layer, and a porous membrane layer disposed therebetween. The sensor body defines an internal liquid reservoir. The membrane layer is fluidly connected with the liquid reservoir, and extends to an outside edge of the microtensiometer. The membrane layer defines a plurality of through pores providing an open path from the liquid reservoir to the outside edge of the microtensiometer. The pores have a maximum diameter of 3 millimeters. The microtensiometer further includes a sensor adapted to measure changes in pressure between the liquid reservoir and an outside environment. The temperature sensor is integrated onto the microtensiometer body, and the water content sensor is coupled to the microtensiometer body.

Multimodal sensor including a tensiometer, method of use and fabrication

A microtensiometer sensor includes a substrate layer fluidly coupled to an enclosed reservoir. A porous membrane is disposed on a surface of the substrate layer. The membrane defines a liquid side fluidly coupled to the reservoir and a vapor side fluidly coupled to a vapor interface. The porous membrane includes a plurality of through holes fluidly coupling the liquid reservoir to the vapor interface, and a nanoporous filler material disposed within the plurality of through holes. The filler material includes a plurality of open pores having a maximum diameter in the range of 0.2 to 200 nanometers. In one embodiment, the microtensiometer sensor includes a molecular membrane disposed adjacent to the vapor side of the porous membrane. In one example, the molecular membrane is formed of a highly crystalline polytetrafluoroethylene polymer having a microstructure characterized by nodes interconnected by fibrils. In one application, the microtensiometer sensor may be used in a probe to measure the average water potential within a network of plant or tree xylem. In another application, the microtensiometer sensor may be useful in real-time determination of the water potential in soil.

Microtensiometer sensor, probe and method of use

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Geneva, NY, United States of America

Alan N Lakso