New optoelectronic devices for the Near and Mid-Infrared spectral range open completely new possibilities for portable sensors creation. Using infrared LED-PD optopairs allows developing an instrument that is smaller, less expensive and energy-saving.

Moisture measurement

Moisture is presence of water in different substances. Moisture measurement is critical because it may affect the business cost of the product and the health and safety of the personnel. There are several different techniques of water detection. We offer method of optical absorption based on mid-infrared LED-PD optopair.
Water has the main absorption band at 1800‒1950 nm (the data are taken from HITRAN Catalogue). We recommend using Lms18LED or Lms19LED LEDs and Lms24PD series photodiode.

Spectra of an LED and a PD for H2O detection:

Our devices can be applied in the following areas:
• Medical applications (respiratory equipment, sterilizers, incubators, pharmaceutical processing)
• Paper and textile production
• Agriculture (plantation protection, soil moisture monitoring)
• Food processing
• Semiconductor industry (moisture measurement during technological processes)
• Domestic applications

Advantages of our devices:
✔  Non-destructive analysis
✔  Possibility to arrange a compact design of an optical cell thanks to compact size of the LED chip – 0.35 × 0.35 mm
✔  No need of using additional optical filters – LED emission band width is comparable to absorption band width of CH4
✔  Low power consumption (<1 mW)
✔  Short response time (10‒50 ns)
✔  Possibility to achieve modulation ranges of up to 100 MHz
✔  Operation temperatures up to +150°C
✔  Lifetime of 80 000 hours

LED-PD based Evaluation systems for moisture measurement
NEW LA-1t LED Analyser a device oriented for the initial experiments with different liquid (and other) substances, enables defining the absorption properties of the analyzed sample in the spectral range 1.3 – 2.3 µm.
LA-1t’s optical module includes:
- 8-element LED array with peak emission wavelengths about 1.3, 1.4, 1.6, 1.7, 1.9, 2.1, 2.2 and 2.3 µm;
- Wideband photodiode with a cut-off wavelength about 2.4 µm and 2 mm sensitive area diameter;
- ZigBee/Bluetooth wireless data transmission module for fast data transfer to a data control center;
- Battery power supply for autonomous operation.

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