Plant water stress detection through the monitoring of short-wave infrared (SWIR) transmittance of a leaf

Institute Reference: INV-21099


The increasingly reduced availability of arable land leads to the need for yield optimization. By 2050, the agriculture industry will face a global 70% increase in food needs therefore, there is a pressing need to increase the efficiency of food production by reducing resource utilization. The collection of high-granularity, real-time data on plants’ condition, would effectively translate into actionable items in order to optimize water usage and crop yield.

However, currently available state-of-the-art water stress sensor technologies cannot be deployed in large-scale crop fields with high granularity due to the short battery lifetime that typically stop working after a few weeks in the field. A mitigation measure is to employ solar panels to recharge the batteries to extend operation time. However, this approach increases the cost, and size of the sensor nodes preventing the scaling for large-area development. In addition to power consumption, drawbacks in terms of inadequate accuracy, low temporal/spatial resolution, high complexity, or bulky size also inherently exist per specific sensor technologies.

Technology Overview

This Northeastern invention is the first micromechanical photoswitch (MP) capable of detecting water-stress in a plant by monitoring its leaf’s infrared transmittance change without consuming any electrical power in standby.

The detection mechanism relies on the dependence of short-wave infrared (SWIR) transmittance on the leaf relative water content (RWC), a parameter that denotes the water‑stress level of the plant. The leaves of non-water-stressed plants have low transmittance in the SWIR region (1.3 - 1.6μm) due to strong IR absorption by water inside the leaf. As such, the lower the RWC, the higher the transmitted IR power is through the leaf. To achieve this, the proposed detector employs an MP with an integrated high-efficiency narrowband IR plasmonic absorber (η ~93%, bandwidth ~10%) matched to one of the water’s spectral absorption bands (λ = 1.47μm). 

The MP essentially functions as an IR- triggered switch that keeps the load electronics (e.g., a wireless transmitter) physically disconnected from the battery until it closes. Owing to the use of miniaturized components, the inventors envision a real-life deployment scenario of the sensor as a paperclip-like device that attaches to a leaf.



  • zero standby-power
  • plant water stress detection through the monitoring of short-wave infrared (SWIR) transmittance of a leaf
  • integrated high-efficiency narrowband IR plasmonic absorber
  • miniaturized components
  • maintenance costs such as battery replacement can be eliminated

Measuring the irrigation needs directly from the leaf guarantees:

  • the right amount of water required per growth stage leading to yield optimization + water usage optimization
  • gets rid of the type-of-soil and depth-of-roots calibration steps


  • Precision Agriculture: large scale deployment in crop fields with fine spatial granularity 
  • Provide a cost effective solution in areas where salinity of the soil is too high to use common soil moisture sensors
  • Greenhouses
  • Substitute duty cycled water pumps in “at home plants care”
  • Landscaping for big institutions


  • License
  • Partnering
  • Research collaboration


  • Development partner
  • Commercial partner
  • Licensing

IP Status

  • Provisional patent


Patent Information:
For Information, Contact:
Rhonda Kivlin
Intellectual Property Administrator
Northeastern University
Antea Risso
Sila Calisgan
Vageeswar Rajaram
Sungho Kang
Zhenyun Qian
Matteo Rinaldi
Leaf Transmittance
Plant Water Stress
Remote Sensing
smart farm
Zero Power