An inexpensive universal fluid cell for atomic force microscopy

Atomic force microscopy (AFM) is a powerful instrument for researching biological phenomenon at the nanoscale. A fluid cell can be used to hold the bacteria and fluid. As many biological processes occur in fluid environments, need to be kept hydrated for proper analysis, yet commercially produced fluid cells involve complex set up procedures and are expensive. As an integral part of a Research Experience for Teachers (NSF RET) summer program, we created an inexpensive fluid cell molded from polydimethylsiloxane (PDMS) with embedded silicone tubing and an attached glass cover slip at the bottom. The device was designed and assembled within 6 weeks with several revisions occurring in the following weeks. The objective of this work was to design an AFM fluid cell that allows for the exchange of fluid, is inexpensive to produce and reproduce, is sterilizable and is easy to set up and use. After multiple design iterations and testing of prototypes, we validated the device by examining peptide-membrane interactions using an AFM equipped with the fluid cell. This device will aid researchers by providing an inexpensive, simple means of investigating and analyzing various biological samples in an AFM.