Novel bioelectronic interface achieved by coupling an integrated circuit with bacterial-flagellar-motor-rotation

The bacterial flagellar motor is one of nature’s rare molecular machines. Its direction of rotation is regulated by the chemotactic network, which can sense down to nanomolar concentrations of specific chemicals on the time scale of seconds. The motor can thus serve as a biosensor with unprecedented speed and sensitivity. However, at the resolution needed motor speed and rotational direction are currently detected optically, using complex equipment. A step change in harnessing the sensing potential of the motor and associated signalling network is to detect its rotation electrically and with high throughput. Here we demonstrate such detection using a custom-designed integrated circuit (IC) with micron-sized electrodes.

Our bioelectronic transducer is based on a single bacterium with a rotating motor attached close to a set of micron-sized electrodes, which is then probed with a high-frequency voltage to measure the impedance change due to the rotating flagella. The frequency of impedance changes we obtain coincides with the speed of rotation seen optically. To assist the liquid delivery to the electrodes and the IC, whose area is roughly the size of mm², we use a two-layer microfluidics channel with customised geometry. The technology has the potential to revolutionise whole-cell biosensors and their application, because it offers electrical readout, while at the same time bioengineering of whole cells promises to significantly expedite the redesign for sensing of novel analytes.