Provided are devices and methods for detecting the presence, absence, and/or characteristics of bacteria. A microfluidic device for characterizing bacteria is provided. The device contains one or more bacteria trapping channels, and one or more pneumatic channels in contact with the bacteria trapping channels, wherein the one or more pneumatic channels are configured to reduce the height of the one or more bacteria trapping channels to thereby trap bacteria in the one or more bacteria trapping channels if said bacteria are present in a liquid biological sample that is introduced into the microfluidic device. Also provided is a method for identifying bacteria that may be used with the microfluidic device.