Droplet networks with incorporated protein diodes show collective properties

Recently, we demonstrated that submicrolitre aqueous droplets submerged in an apolar liquid containing lipid can be tightly connected by means of lipid bilayers(1-5) to form networks(4-6). Droplet interface bilayers have been used for rapid screening of membrane proteins(7,8) and to form asymmetric bilayers with which to examine the fundamental properties of channels and pores(9). Networks, meanwhile, have been used to form microscale batteries and to detect light(4). Here, we develop an engineered protein pore with diode-like properties that can be incorporated into droplet interface bilayers in droplet networks to form devices with electrical properties including those of a current limiter, a half-wave rectifier and a full-wave rectifier. The droplet approach, which uses unsophisticated components (oil, lipid, salt water and a simple pore), can therefore be used to create multidroplet networks with collective properties that cannot be produced by droplet pairs.