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A miniaturized microfluidic device was developed to facilitate electromanipulation of bacterial respiratory pathogens. The device comprises a microchip with circular aluminum electrodes patterned on glass, which is housed in a microfluidic system fabricated utilizing polydimethylsiloxane. The device provides sample preparation capability by exploiting positive dielectrophoresis (DEP) in conjunction with pulsed voltage for manipulation and disruption of Bordetella pertussis bacterial cells. Positive DEP capture of B. pertussis was successfully demonstrated utilizing 10 Vrms and 1 MHz ac fields. Application of dc pulses (300 V amplitude and 50 micros pulsewidth applied 1 s apart) across the aluminum electrodes resulted in electrodisruption and lysis of B. pertussis bacterial cells. Real-time polymerase chain reaction, a 2(3) factorial experimental design and transmission electron microscopy were used to evaluate bacterial cell manipulation and factors affecting bacterial cell disruption. The main factors affecting bacterial cell disruption were electric field strength, the electrical conductivity of the cell suspension sample, and the combined effect of number of pulses and sample conductivity. The bacterial deoxyribonucleic acid target remained undamaged as a result of DEP and cell lysis experimentation. Our findings suggest that a simple miniaturized microfluidic device can achieve important steps in sample preparation on-chip involving respiratory bacterial pathogens.

Twenty-four-hour ambulatory pH monitoring is an essential tool for diagnosing gastroesophageal reflux disease (GERD). Simultaneous impedance and pH monitoring of the esophagus improves the detection and characterization of GERD. Conventional catheter-based monitoring systems are uncomfortable and interfere with the normal activity of the patient. To overcome these disadvantages, different wireless esophageal monitoring systems have been proposed. A capsule containing sensors for impedance and pH monitoring with wireless communication capabilities is presented. A low cost miniature microcontroller was utilized for interfacing between the sensors and a wireless transmitter. The microcontroller program allowed efficient management of the electric power provided by a 3-V battery. Magnetic holding is proposed as an alternative to surgical affixation of the monitoring capsule. Permanent neodymium magnets separated by 27 cm successfully held the capsule in a test tube. Experimental results demonstrated that friction force can aid magnetic holding to overcome peristalsis. The proposed design efficiently detected acid and nonacid reflux. More research regarding the holding method and capsule packaging are necessary to optimize the mechanical performance of the proposed design in order to facilitate clinical testing on human subjects.