Modeling and control of a programmable filter for separation of biologically active molecules

We present the modeling and control of a programmable filter applicable to the separation of biologically active molecules like proteins and DNA. Conventional methods of separation are bulky, costly and time-intensive. We propose a diaphragm valve design that can filter molecules based on their size by controlling a narrow gap formed between two flat parallel plates. Modeling and experiments performed on a prototype implementation of the gap are presented. Preliminary tests performed on our closed-loop control system indicate that a resolution of 0.2 nm can be achieved for the gap size. Further, to account for any tilt between the plates, we propose the design of a flexure that can compensate for the tilt and ensure the formation of a uniform gap. Dynamic modeling of the flexure and simulations of the tilt-compensation are presented.