Electrochemical microdevice for the determination of the minimum inhibitory concentration of antibiotics

Antibiotics are useful for treatments of a wide variety of infections. However, their performance has not been fully exploited because of a lack of approaches to rapidly select appropriate antibiotics and their concentrations. In this study, we propose a microsystem that can be used for rapid and on-site selection of antibiotics. The device consisted of a glass substrate with thin-film sensing electrodes and a polydimethylsiloxane (PDMS) substrate with two microchannels and eight culture chambers. The microdevice was designed to evaluate growth of microbes using impedance measurements or optical imaging under different conditions of antibiotics. There was a good correlation between these measurements on the monitoring of the growth. The minimum inhibitory concentration (MIC) of gentamicin against E. coli was determined within 12 h with both measurements. Because the electrochemical approach will provide a portable and inexpensive system compared to the optical approach, the microdevice using impedance measurements may provide a promising tool for on-site rapid selection of antibiotics.