The poor man's trough: a benchtop, motor-free method to 3D Langmuir-Blodgett films

Langmuir-Blodgett troughs provide an excellent system to deposit monolayer films onto flat and curved substrates. However, most trough designs use motorized barriers to compact the film, and it is difficult to fully eliminate the capillary waves and striations on deposited films caused by motorized barriers. Here, we present an inexpensive design for a benchtop LB trough that compresses the film without motorized barriers; instead, it is the trough's geometry that compresses the film in a drainage basin. We demonstrate this approach with a 3D printed drainage basin and with self-assembled polystyrene colloidal films on a range of 3D glass substrates: a jar, a bulb, and a compressor tube. We provide a mathematical formalism to coat 3D objects with arbitrary size and shape; especially with facile 3D printing, this concept may be extended in a cheap and modular approach.