Although valves and pumps exist to control flow in microfluidic channels, they are not easy to miniaturize further for use on nanometer levels, says Berkeley mechanical engineer Arun Majumdar.

• 柏克莱的机械工程师马强达（ArunMajumdar）指出，虽然现在已有阀门和帮浦可用来控制微流体通道中的液流，但要进一步缩小以便在奈米等级下使用则很难。