Dual Beam Atomic Force Microscope

A major problem in AFM is unpredictable drift between the cantilever and surface which sacrifices the integrity of long timescale measurements such as the process of actin network growth. In order to minimize this problem we constructed a force microscope in which two cantilevers, mounted on the same rigid substrate, are monitored simultaneously. One cantilever is used to measure sample changes and the other is used as a sensor to compensate for unwanted surface drift.

Optical Trap

Optical trapping is a technique that uses light to position microscopic objects. Forces that result when an intense beam of light strikes a small object trap it, allowing the beam to "hold" the particle. In the biological sciences, optical traps—also known as optical tweezers because they are used to manipulate small objects—have been used to apply forces in the pN-range and to measure nanometer-scale movements of objects ranging in size from 10 nm to over 100 µm. Optical tweezers have been used to trap viruses, bacteria, living cells, organelles, small metal particles, dielectric (electrically nonconducting) spheres, and even strands of DNA. Applications include confinement and organization (e.g., for cell sorting), tracking of movement (e.g., of bacteria), application and measurement of small forces, and altering of larger structures (such as cell membranes). Two of the main uses for optical traps have been the study of molecular motors and the physical properties of DNA.

Microjet

We are developing a microjet based on a piezoelectric actuator that can achieve jet velocities up to 140 m/s and can penetrate soft tissue. The microjet is an improvement on needle-free drug delivery because it can control penetration depth and volume electronically. By controlling nozzle sizes (20 – 120 microns) and stand-off distances, we can adjust the jet for precise and painless shots.