Ultraviolet laser ablation of polymers: Yield and spatial distribution of products deposition

Photomodification of polymer microchannels induced by static and dynamic excimer ablation: effect on the electroosmotic flow

This paper presents a study of polymer surfaces modified by laser ablation using poly(ethylene terephthalate) (PET) as a model system. The surface properties induced by static and dynamic ablation with the 193-nm pulsed radiation of an ArF excimer laser (4 x 10(7) W/cm2) in air have been successfully used to control the electroosmotic flow (EOF) in photoablated PET microchannels. Through the creation of well-defined static ablation patterns onto the walls of a trapezoidal channel, it was found that the resulting reduction in the EOF could be controlled. For example, a reduction of 25% in the EOF was observed in 42-microm-deep microchannels when using a static ablation pattern treating 50% of the total wall surface area. A numerical study describing the fluidic behavior induced by a static pattern is also presented. Moreover, X-ray photoelectron spectroscopy has been used to point out surface changes between static and dynamic ablation, thereby demonstrating an ability to create new functionalities in microchannels by laser treatment.

Development of a Simple and Highly Sensitive Microbalance for Measurements of Total Particle Yields in Matrix Assisted Laser Desorption

In order to open a new window for getting insight into the process of matrix assisted laser desorption ionization (MALDI) of biopolymers, a highly sensitive quartz crystal microbalance (QCM) was developed to measure desorption yields of neutral particles. For the matrix substances commonly used the mass resolution of 0.95 ng obtained with the balance corresponds to a detection limit of ∼1012 particles.