Controlling the contents of microdroplets by exploiting the permeability of PDMS

A microfluidic device capable of exploiting the permeability of small molecules through polydimethylsiloxane (PDMS) has been fabricated in order to control the contents of microdroplets stored in storage wells. We demonstrate that protein precipitation and crystallization can be triggered by delivery of ethanol from a reservoir channel, thus controlling the protein solubility in microdroplets. Likewise quorum sensing in bacteria was triggered by delivery of the auto-inducer N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL) through the PDMS membrane of the device.