Fluid sensor has automatic calibration circuitry

Optek Technology has launched the OCB350 fluid sensor, which features automatic calibration circuitry and is available with multiple output states.

These include 'fluid present', 'no fluid present' and 'no tube present'.

The sensor is ideal for medical applications including monitoring fluid or air presence in tubing for infusion and transfusion pumps where fluids of different optical densities are used.

Roland Chapa, vice-president of optoelectronic integrated solutions for TT Electronics Optek Technology, said: 'The OCB350 series sensors are designed to maintain the calibrated setting even if power is lost.

'Once calibrated, the setting will remain constant, allowing for faster start-up.

'The self-calibration feature allows the sensor to easily adapt to changes in fluid type, outperforming more expensive ultrasonic sensors,' he added.

Designers can initiate the calibration procedure at any time by grounding the J1-pin-4, which allows the device to be remotely calibrated and then mounted in the equipment.

When the system calibrates the sensor, it raises the current through the LED from 0mA to 14mA, until the phototransistor reaches the preset point.

The OCB350 series sensor consists of an infrared LED and phototransistor packaged in an opaque plastic housing that enhances ambient light rejection.

The housing features an opening designed to accommodate clear tubing with outer diameters of 0.0625in (1.6mm), 0.125in (3.2mm) or 0.1875in (4.8mm).

The presence of clear liquid causes the phototransistor to sink the maximum current, while the presence of dark liquid causes it to sink the minimum current.

As bubbles pass through the tube, the signal will vary between the 'liquid present' and 'no liquid' states.

If no tube is present, the phototransistor sinks current between the dark fluid and clear fluid states.

The infrared LED features a forward DC current of 50mA with a peak current of 1.0A.

Reverse DC voltage is 2.0V and power dissipation is 100mW.

The output phototransistor features a maximum collector-emitter voltage of 24V or 30V, with collector DC current of 50mA and power dissipation to 100mW.

Operating temperature range is from -40C to +85C.

Back to top