Soft/wet microrobotics researches are developed along 2 axis: fluidic or capillary microrobotics (based on physics of fluids) and flexible microrobotics (based on elasticity and materials).
- Scientific questions relate to physics of fluids and materials
- Methods relate to mechanical engineering: modelling and simulation, manufacturing (down to 200nm), design, dynamics and control, experimental force measurement (down to 1nN)
- Applications fields cover micromanipulation, drug delivery, medical devices, industrial micro-assembly.
Fluidic and capillary microrobotics
- Thermocapillary micromanipulation: a 2°C temperature increase of the free surface (generated by a IR laser) leads to surface stresses inducing thermocapillary flows which can be use to handle floating particles without contact.
- Open loop proof of concept
- Step response
- Stationary velocity
- Feedback control (1–2)
- to come: laser patterns
- to come: feedforward control for Cheerios effect reduction
- Cheerios effect: floating particles are attracted by Cheerios forces, which can be compensated in micromanipulation by feedforward robotics strategies
- Drobotics = Droplet Microrobotics: 3 bubbles in liquid or 3 droplets in air can support and actuate a millimetric platform with 3 degrees-of-freedom. Applied force can be estimated from the droplets heights deduced from electrical resistance
- Electrosprays: Liquid handling technique generating aerosols for drug delivery
- Bio-inspired elasto-capillary adhesion: Coupling between capillary and elastic forces are used by some insect to control their adhesion. This phenomenon has been studied « in vivo » on dock beetles (cover page of JRSI) and « in vitro » in engineered elastocapillary systems
- Capillary microrobotics: Capillary forces can be used to align components or to grip them in pick-and-place processes
- Capillary forces in granular media: Capillary bridges are well known by kids to build sand castles. More generally, capillary forces act in granular media, in so-called pendular and funicular regimes
- Liquid handling: Small quantities of liquid can be manipulated by liquid dielectrophoresis (LDEP 15µm droplets, done in U Tokyo) or capillary bridges (handling of µL with conical tip)
- Compliant actuators
- 4D department logo with shape memory polymers (SMP)
- Shape memory polymer trombone
- Shape memory polymer hand
- Bending of medical catheter
- Tunable stiffness mechanisms: Loïc
Other topics: Micromanipulation, Nano-Actuators and Microfabrication
- Acoustic forces for non-contact manipulation: in acoustic levitation, (sub)millimetric components can be stably stored in pressure nodes of acoustic standing waves. The description of these works is published in Precision Engineering and in Journal of Applied Physics, and highlighted in Physics Today.
- Levitation of a steel washer
- Levitation of a liquid droplet
- Levitation of multiple components
- Acoustic levitation in combination with a capillary gripper to extract the component out of the acoustic chamber
- Stick-and-slip nano-actuators: the coupling between inertia and friction allows the development of long cm rang actuators with nm positioning mechanical resolution
- Manufacturing: characterization and combination of additive manufacturing towards advanced multiscale manufacturing, excimer laser manufacturing.
- SEM image of an ablated PMN–PT part with excimer laser. The cone-structure is visible. The cones height vary from 115 to 30µm
- Nanoscribe structures