Plant Science Tools


Handheld Photosynthesis System

The CI-340 Handheld Photosynthesis System is a portable, single-handed tool that measures photosynthesis, respiration, transpiration, stomatal conductance, PAR and internal CO­2. Light-weight and durable, the CI-340 was designed for field use. The optional accessory modules allow researchers to control CO2, H2O, temperature, light intensity, and measure chlorophyll fluorescence, while the ten different customized chambers accommodate any leaf size, including conifer needles and cacti. Direct chamber connection to the CO2/H2O gas analyzer reduces measurement delay and enables rapid measurement of gas exchange with minimal delays.

Click here for a downloadable compilation of published research.

Theory of Operation


Photosynthesis is the formation of carbohydrates from CO2 and a source of hydrogen (as water) in the chlorophyll-containing tissues of plants exposed to light. Photosynthetic rate is determined by measuring CO2 before and after it enters the leaf chamber to calculate the rate of CO2 assimilation by a known leaf area.
See the calculation.


Transpiration is the movement of water vapor from leaf tissue into the atmosphere. Transpiration rate is determined by measuring water vapor before and after it enters the leaf chamber to calculate the rate of water vapor flux per one-sided leaf area.
See the calculation.

Stomatal Conductance

Stomatal conductance refers to the openness of the leaf stomata determines the rate of CO2 assimilation into the leaf and water vapor exits the leaf through the stomata. Stomatal conductance is calculated by measuring transpiration rate as a function of leaf temperature.
See the calculation.

Open or Closed System

The CI-340 is easily operable as either an open and closed system. In open system measurement, the incoming gas is drawn from the ambient, or control-module altered, air and the exhaust returns to the external atmosphere. During closed system measurements, the air is recirculated from the exhaust back into the chamber.
See the calculation.

Absolute and Differential Readings

The CI-340 is designed to measure both absolute and differential readings. In Absolute Mode, the CI-340 measures gas concentrations from a single source. For differential measurements, the concentration of gases from both the inlet of the chamber and the chamber exhaust are measured.

Glossary of Abbreviations


  • Lightweight and optimized for single-handed operation
  • Stable analyzers for accurate CO2 and H2O measurements
  • Accommodates open and closed system measurements
  • Infrared, non-contact leaf temperature sensor
  • Ten interchangeable chambers customized for different leaf types
  • Custom soil respiration chamber
  • Control modules for light, temperature control, CO2 / H2O supply and chlorophyll fluorescence measurement
  • Chlorophyll fluorescence and photosynthesis measured simultaneously


Main Unit

Main Unit: On board IRGA for CO2 Analysis,
2O Analysis with humidity sensor capacitor,
Flow Control, Pump, Display and Key Board,
Leaf Chamber attachment ports and Battery.

Display: LCD 40 x 6 characters or 320 x 64 pixel

Data Storage: 4 MB Internal FLASH RAM

Data Output: USB

Flow Rate: 100 ~ 1000 cm3 / min

Operating Temperature: 0-45° C

Operating RH: 0-90% non-condensing

Power Supply: 7.2 VDC, 4400 mAh for 5 hours continuous use,
extended hours of use with additional batteries.
AC Adapter / Battery Charger supplied.

Weight: 1.5 Kg (3 Lbs) with Battery

Dimensions: 44 cm x 5.5 cm x 5 cm

CO2 Analyzer

Sensor: Low power Non-Dispersive Infrared Gas Analyzer

Chopping Frequency: 1 Hz

Sensors Response Time: 35 seconds

Source Life: 5,000 hours

Measuring Range: 0 to 2000 ppm (Standard) - 0 to 3000 ppm (Optional)

Resolution: 0.1 ppm

Repeatability: ±0.1 ppm (short term)

Accuracy: < ± 2% up to 2000 ppm

Sample Cell: 100 mm x 10.2 mm (3.94” L x 0.40” Dia)

H2O Analyzer

Sensor Type: Humidity Sensitive Capacitor

Stability: Stable Analyzer for accurate H20 measurements

Measuring Range: 0 to 100%

Resolution: 0.1%

Accuracy: ±2% at 10% RH, ±3.5% at 95% RH

PAR Measurement

Sensor Type: Filtered GaAsP - Photodiode

Measuring Range: 0 ~ 2500 µmol m-2s-1

Accuracy: ±5 µmol 0-2500 µmol / m/ sec

Chamber Temperature Measurement

Sensor Type: Thermocouple

Display: LCD 40x6 characters 320x64 pixel

Measuring Range: -15 ~ 50°C

Accuracy: ±0.1°C

Leaf Temperature Measurement

Sensor Type: Infrared Sensor

Measuring Range: -10 ~ 50°C

Accuracy: ±0.3˚ C

How to Use it

To measure photosynthetic activity, simply secure a leaf within the CI-340 chamber to measure leaf gas exchange under ambient conditions or in a closed system. Data is available in moments as the CI-340 sensors work together to record and calculate gas exchange according to customizable research parameters.

Adding control modules to the CI-340 enables complete environmental control in field or lab settings, where CO2, H2O, light and temperature can be altered to measure plant response.

CI-340 training Power Point

CI-340 Use Case w/ Dr. Olyssa Starry

In the Box

The CI-340 Handheld Photosynthesis System includes:

  • Handheld photosynthesis analyzer—display, keypad, computer, data memory, CO2 and H2O gas analyzers, flow control system, and battery.
  • Leaf Chamber (default LC-1)
  • PAR sensor
  • Infrared temperature sensor
  • Soda lime and Silica Gel tubes
  • Spare part kit
  • Rechargeable battery and charger
  • USB cable
  • Communication software
  • Operation manual
  • Instrument case
  • 1st year of annual maintenance (USA only)

Optional Control Modules:

  • Temperature
  • CO2 and H2O
  • Light
  • Chlorophyll Fluorescence

Optional Leaf and Soil Respiration Chambers available on accessory page.

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