Microfluidic bubble detector - MBD

Microfluidic Bubble Detector

Optical microfluidic transmittance sensor

Liquid optical specificities detection

Detection based on a transmittance analogical measure

Bubble detection

Can easily detect air bubbles

Features & Benefits

The most-popular application for the Inline Liquid Sensor is to use the sensor as a microfluidic bubble detector. Bubbles are a big challenge to address in microfluidics, as they can induce flow modifications or interact with the experiment and damage to the sample. Users can monitor and count the passage of microfluidic bubbles at any given point of their setup and automate the experiment accordingly.

For example, when paired with an OB1 it is possible to increase the pressure or switch a valve to direct the bubbles into another fluidic path.

Benefits

Reliable non invasive technique
Cost effective compared to camera check
Based on true/false logic
Compatibility with both 1/16″ or 1/8″ OD tubing
Use anywhere in your setup
Setup automation: it is possible to trigger fluid control operations based on the signal

The Inline Fluid Sensor can be plugged directly onto Elveflow’s OB1, or it can be used as a standalone unit with the Sensor Reader.

Applications

Bubble detection
Liquid detection
Bilateral recirculation based on liquid-air detection
Switch condition for unilateral recirculation
Automatic sampling set-up
How to use the Elveflow microfluidic bubble detector? [Application Note]
Air bubbles and microfluidics: Tips and tricks to remove them [Review]

Example: Bilateral Medium Recirculation

Based on the liquid detection principle, you can perform Medium recirculation without any recirculating valve, using the Inline optical sensor, the OB1 flow controller and our sequencer using the all-in-one ESI software. Next, we will show you a smart and easy way to perform bidirectional recirculation without using valves.

Materials:

Pressure source
Elveflow® pressure & flow control instrument (OB1)
Sample reservoirs and tubing (a small reservoir, medium reservoir or a large microfluidic reservoir), one for each medium sample
Microfluidic chip (here an organ on a chip microfluidic chip from Aline Inc…)

Procedure:

Using the Elveflow scheduler (see below figure), you can easily automate your setup by using elementary steps like applying a pressure profile, taking conditional actions and detecting bubbles. We present here the experimental protocol with the corresponding scheduler steps.

Apply pressure on line 1: STEP 1.
When tube 1 is empty, bubbles will appear.
The liquid sensor 1 detects the bubbles and then pressure in line 1 is turned off. Simultaneously a pressure is applied in line 2 => STEP 3 & 4
Then, when the tube 2 is empty, bubbles will appear.
The liquid sensor 2 detects the bubbles and the pressure in line 2 is turned off. Simultaneously, a pressure is applied in line 1 => STEP 6 & 7
The experiment can be continued as many times as you want.

Principle of operation

The Inline Fluid Sensor detection principle is based on the measurement of the optical path and the variation of this path when the flowing medium is changing.

A light beam is emitted by a LED of known power. This light beam goes through the capillary and the fluid flowing through. It is then collected by an NPN silicon phototransistor which converts the light power into an electrical signal. When a the fluid changes, the optical index and the light absorption coefficient change accordingly. It induces a change in the electrical power and allows detection of changes in the fluid.

ESI is Elveflow’s advanced software interface, built to make experimenter’s life better. It is perfectly adapted from simple setups control to very advanced setups and workflows automation. It integrates several modules that make time-consuming and painful tasks so simple. It comes with SDK libraries to control the Elveflow system with your own code.