We levitate micron-scale particles made of several different materials ranging from ceramic to polymethylmethacrylate (PMMA) with a vertical temperature gradient inside a rarefied gas chamber. Collisions with energetic gas molecules from below provide a net upward momentum transfer, generating a thermophoretic force that allows us to stabilize the particles a few millimeters above a hot plate. In the appropriate pressure regime (1~10 Torr), we can stabilize them for up to two hours. With the help of a laser, we are also able to modify the temperature gradient around the particle, providing an additional photophoretic force. Our future goals are to trap the levitated particles inside an optical lattice to control their movement and to develop a model that fully explains single-particle motion and multi-particle interactions.
Meet the team
Left to right: Stella Kraus, Joao Henrique Oliveira Fontes, Cheng Chin, Andrew Reynoso
Close-up image of levitated PMMA particles
Two levitated PMMA particles
Many levitated PMMA particles forming a disk
Single levitated PMMA cluster of spheres with laser interference pattern in the background