A parallel diffusion-based microfluidic device for bacterial chemotaxis analysis.

We developed a multiple-channel microfluidic device for bacterial chemotaxis detection. Some characteristics such as easy operation, parallel sample adding design and fast result readout make this device convenient for most biology labs. The characteristic feature of the design is the agarose gel channels, which serve as a semi-permeable membrane. They can stop the fluid flow and prevent bacteria getting across, but permit the diffusion of small molecules. In the device fabrication process a novel thermal-based method was used to control the shape of agarose gel in the microfluidic channel. The chemical gradient is established by diffusion which can be precisely controlled and measured. Combined with an 8-channel pipette, different attractants, repellent chemicals or different bacteria were analyzed by a two step operation with a readout time of one hour. This device may be useful in the high throughput detection of chemotaxis related molecules and genes.