Daily Archives: August 31, 2022

Digital Planar Liquid Flow Sensor

The chemical industry often requires measuring liquid flow in fluidic manifold systems. These often involve high-volume applications but with severe space limitations. For such applications, Sensirion offers a digital planar liquid flow sensor, the LPG10-1000. The sensor uses a planar microfluidic glass substrate that has down-mounted fluidic ports. Measuring only 10 x 10 x 2.35 mm, the LPG10-1000 is a highly compact unit capable of being integrated into any fluidic manifold system.

The sensor combines a digital microsensor and a microfluidic chip to measure the liquid flowing inside the planar glass substrate. The presence of the digital microsensor chip ensures full signal processing functionality. Its digital output is linearized, temperature compensated, and fully calibrated.

LPG10-1000 from Sensirion is an intelligent sensor providing solutions for measuring flow rates from a few microliters per minute to about 1ml per minute. Sensirion has provided a special glass for the wetted material, and it ensures optimum compatibility with the pharmaceutical and biological processes. The low thermal mass of the sensor allows response times lower than 30 ms. The sensor has built-in features for detecting real-time failures like leaks, air bubbles, and clogging.

The Sensirion sensor LPG10-1000 offers several advantages for measuring liquid flow. Its tiny size makes it extremely convenient for integration, even in small spaces. The engineering simplicity of the sensor’s design offers excellent repeatability. The output signal is digital, linearized, and calibrated. Media compatibility is excellent, and chemical resistance is high.

Sensirion has used the media isolated sensing principle for its sensor, as there is no direct sensor contact with the fluid it is measuring. The glass they use is of the inert type, so it is bio-compatible with the chemical process. The sensor offers a digital I2C interface for electronic compatibility.

The LPG10-1000 sensor offers a full-scale flow rate of 1000 microliters, and a sensor output limit of 1500 microliters. The response time for detecting the flow is about 40 ms, with 120 ms from power-up. The operating range for the sensor covers +5 to +50 °C, while the specified temperature range for storage is -40 to +60 °C. The sensor can operate reliably in 0 to 95% humidity and non-condensing conditions. The recommended maximum operating pressure is under 3 bar or 43 psi, and the sensor can withstand a burst pressure of up to 7 bar or 101 psi.

For a full-scale 16-bit output, the digital sampling time of the sensor is 74 ms. However, for a 9-bit output, the sampling time can drop to as low as 1 ms. The sensor operates within a supply voltage range of +3.3 to +3.6 VDC, consuming less than 6 mA operating current.

The internal substrate channel glass material is borosilicate and has a down mount fluidic connection. The introduction of the sensor in a fluidic manifold system causes a pressure drop of only 0.1 millibars at full-scale flow rates. The total internal volume of the sensor is about 11.7 microliters. The cross-sectional flow channel of the sensor measures about 0.9 x 0.9 mm, and the total mass of the sensor is only 0.32 grams.