Thermal conductivity sensor - TCS205

  • Thermal conductivity sensor
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• Thermal conductivity sensor for gases
• Silicon micromechanics
• Very small dimensions
• Short time constants
• Measurement of very small gas volumes
• Gas exchange by diffusion

  • Model Number: TCS205
  • Data Sheet: Date Sheet File
Quantity:
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Product Specification

DESCRIPTION:

    The sensor element consists of a silicon chip with a thin membrane approximately 1mm2 in size of a material with extremely good electrical and thermal insulating properties. On the membrane are two thin film resistors (Rm1, Rm2) which are both used for heating the membrane and for measurement of membrane temperature Tm.

    The resistors are passivated to protect them from the effects of the gas. The membrane is completely covered by a second small silicon chip with a rectangular cavity etched in. The hollow space thus formed above the membrane is the thermal conductivity section. The gas comes to the measuring section through a small lateral opening in the membrane cover by diffusion only, and not by flow.

    The sensor chip and its cover are attached to a silicon support which also permits gas exchange to the lower side of the membrane. The sensor is electrically connected to an eight pin base by gold wire bonding.

    Due to the thermal conductivity l of the gas surrounding the membrane, thermal energy is dissipated from the membrane held at higher temperature Tm. Measured is the signal needed in a temperature stabilization circuit to keep the excess temperature of the membrane DT constant.

    On the solid part of the chip are two more resistors (Rt1, Rt2) to measure and compensate for the effect of the ambient temperatur.

 

FEATURES:

Measuring hydrogen content thermal conductivity

Analyzing binary gas by evaluating

Determination of CO2 vs. Methane

Discrimination of natural gas

Measurement of Helium or Xenon contents

 

APPLICATIONS:

Industrial application

Monitoring of gas characteristic

Determining gas concentration

Landfill or digestor gas

Different origin gas or compositions gas

 

ABSOLUTE MAXIMUM RATINGS:


SPECIFICATION:


Base material:Silicon, microstructured by anisotropic etching

Material of parts exposed to gas:Si, SiNx, gold, epoxy

Mechanical stress tests have been performed on prototype sample devices for:

Vibration:in accordance with IEC 68-2-6 Appendix B (1982) 10 cycles;

                 ±1.5mm; 20g; 10...2000Hz; 1octave/min
Shock:in accordance with IEC 68-2-27 Amendment #1 (Oct.82) 10
             shocks each radial and axial; 100g; 7.5ms / 300g; 2.5ms / 900g; 1.2ms




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