MICROTECH - OPTOFLUIDICS - Non-contact micromanipulation using thermocapillary convection (1)
The manipulation of particles in the mesoscale range (100 - 1000 μm) is a challenge without an optimalsolution until now. The transposition of known principles from other scales (larger or smaller) is notappropriate because different physical phenomena are important at this respective scale. Therefore, there is a need to develop new manipulation techniques adapted to this scale, among which we can differentiate between contact (end effector is in contact with the object) and non-contact manipulation techniques (end effector uses a force field to manipulate the object). Regarding the non-contact manipulation techniques, there are different physical principles which can be used to generate force fields: electric fields, electro-magnetic fields, acoustic fields, light refraction (optical tweezers), actuated flows, etc.
This work proposes to use laser-induced thermocapillary flow to manipulate particles at the water/air interface. A laser is pointed to a given point in the water interface where it is absorbed and heats the surface generating a thermal gradient which also generates a surface tension gradient which drives the flow movement.