Proposed DEP-Raman device for simultaneous trapping and identification of bacteria

Typical bacterial identification methods can take several days to complete. In order to reduce analysis time, researchers have used a variety of methods for bacterial identification such as polymerase chain reaction, Raman spectroscopy, fluorescent in situ hybridization, and micro-array testing. Although these methods have successfully decreased bacterial analysis time from days to a matter of hours, they require a pure sample or a way to label bacteria with fluorescent tags, antibiotics, or primers. Pure samples require a number of purification steps that lead to loss of sample, and appropriate fluorescently-marked antibodies increase costs and wasted materials due to the broad range of bacteria strains that cause infections and disease. As such, label-free isolation and identification methods like dielectrophoresis (DEP) and Raman spectroscopy are appealing to reduce costs and increase simplicity and efficiency. DEP is the motion caused in a particle as it passes through non-uniform electric field and can be used to sort, isolate, and trap particles. This study successfully demonstrates simultaneous trapping and identification of 3.3 micrometer polystyrene spheres using DEP and Raman spectroscopy. It is proposed that the DEP-Raman device can be developed to sort and identify bacteria from a mixed sample in a matter of minutes leading to prompt and accurate treatment