Filters Residual Life Indication

Today most filters are still replaced by scheduled maintenance, since no viable RLI sensor is yet available. Some filtration systems, like inside HVACs, may employ Differential Pressure Sensors which provide an indirect measurement of a filter approaching saturation. However these have major shortcomings, a cumbersome mechanical installation since they need a by-pass to the main fluid path, which makes them expensive and unusable for mission critical safety applications. Use of Differential Pressure Sensors is relegated to particle filters since they cannot be applied to vapor filtration, such activated carbon or silica filters.

SENSIPLUS provides a low cost, miniature RLI to all material based filters. Our product can be applied universally to HEPA, Fiber, Paper and Active Carbon or Silica Filters for Oil, Air, Gasoline and Water filtration.

It is an highly accurate, temperature compensated direct measurement of the impedance spectra of the filter as an indications of its saturation.


Supply Voltage 1.5-3.6V
Max Current 0.4mA continuous when reading filter with EIS
Size 3x3mm, 0.8mm thickness
Interface I2C or SENSIBUS, single data wire multidrop sensor array cable interface, 1.5-3.6V
Unique Identifier OTP 48bits Unique Device Identifier, 16bits User Defined
Frequency 3.1mHz to 1.2MHz
Vpp output sinewave 156mV to 2.8Vpp
Coherent demodulation 1st, 2nd or 3rd harmonic
Output Reciprocal of real or imagery component
Wide Measurement Range From ohms to 100MΩ for different filter sizes
Range -40°C to 125°C
Accuracy ±0.1°C



  • All types of carbon and activated carbon filters
  • All types of paper, nylon, fiberglass, polyester, rubber, polypropylene, oil impregnated HEPA filters
  • Medium independent, air, water, oil, gasoline.

Want to be an early partner?