Microheater integrated temperature controllable microfluidic tensiometer for measuring dynamic interfacial tension

A method of measuring temperature-dependent interfacial tensions between two liquids using a microfluidic device, said microfluidic device comprising:

• a microfluidic channel generally extending in a first direction for passing a specimen fluid, microfluidic channel having a constriction portion having a width narrower than a main portion of the microfluidic channel;
• a microheater disposed along the main portion of the microfluidic channel, the microheater being made of a first resistive wire having a first pair of serpentine-shaped portions generally extending in the first direction along respective sides of the main portion of the microfluidic channel, a portion of the first resistive wire connecting the first pair of serpentine-shaped portions at adjacent ends of the serpentine-shaped portions;
• and
• a temperature sensor disposed along the main portion of the microfluidic channel, the temperature sensor being made of a second resistive wire having a second pair of serpentine-shaped portions generally extending in the first direction along the respective sides of the main portion of the microfluidic channel,
• wherein the method comprises:
• introducing a mixture of two liquids in the microfluidic channel so as to form a droplet of one liquid immersed in another liquid and move the droplet in the first direction;
• driving the microheater and feed-back controlling and regulating temperature inside the microfluidic channel by monitoring the temperature via the temperature sensor;
• imaging a deformation of the droplet as the droplet moves in the microfluidic channel using an imaging device;
• and
• calculating an interfacial tension between the two liquids in accordance with the deformation of the droplet imaged by the imaging device.

A temperature-controllable microfluidic tensiometer for measuring interfacial tensions between two fluids, comprising:

• a microfluidic channel generally extending in a first direction for passing a specimen fluid having a droplet of one liquid immersed in another liquid, the microfluidic channel having a constriction portion having a width narrower than a main portion of the microfluidic channel;
• a microheater disposed along the main portion of microfluidic channel, the microheater being made of a first resistive wire having a first pair of serpentine-shaped portions generally extending in the first direction along respective sides of the main portion of the microfluidic channel, a portion of the first resistive wire connecting the first pair of serpentine-shaped portions at adjacent ends of the serpentine-shaped portions;
• a temperature sensor disposed along the main portion of the microfluidic channel, the temperature sensor being made of a second resistive wire having a second pair of serpentine-shaped portions generally extending in the first direction along the respective sides of the main portion of the microfluidic channel;
• one or more controllers connected to the microheater and the temperature sensor to drive the microheater and detect temperature in the microfluidic channel via the temperature sensor, the one or more controllers feed-back controlling and regulating the temperature;
• and
• an imaging device that takes images of the droplet as the droplet moves in the microfluidic channel.