| AVS 61st International Symposium & Exhibition | |
| MEMS and NEMS | Tuesday Sessions |
| Session MN+NS-TuA |
| Session: | Multi-Scale Phenomena and Bio-Inspired MEMS/NEMS |
| Presenter: | Sowmya Subramanian, University of Maryland, College Park |
| Authors: | S. Subramanian, University of Maryland, College Park M.T. Meyer, University of Maryland, College Park Y.W. Kim, University of Maryland, College Park W.E. Bentley, University of Maryland, College Park R. Ghodssi, University of Maryland, College Park |
| Correspondent: | Click to Email |
We present a multi-experiment PDMS based biofilm analysis platform using a valve-actuated microfluidic system, designed to reduce growth variance of in-vitro biofilms to less than 10%. This was achieved by integrating hydraulic push-down valve actuators to section a uniform biofilm grown in a channel by maintaining a single source of bacterial suspension [1, 2]. In this work, we establish a simplified process flow for the fabrication of a multi-depth device mold and demonstrate the high throughput capability of the microfluidic biofilm reactor.
Bacterial biofilms are the primary cause of infections in medical implants and catheters. The widespread use of high doses of antibiotics to treat biofilm infections is leading to the emergence of antibiotic resistant strains, necessitating the development of alternative methods of treatment [3]. However, the experimental evaluation of new treatment techniques is strongly hindered by the stochastic nature of biofilm growth [1]. Therefore, it is required to develop a microsystem that can not only facilitate multi-experiment studies for new treatment evaluation but also enable the growth of uniform biofilms that can be used as reliable controls.
Figure 1 shows a single uniform biofilm grown in the horizontal center channel of the device is sectioned into multiple sections, by hydraulically actuating the push-down valves thereby enabling multi-experiment studies on the same biofilm. Figure 2 shows the schematic of the operation of a “push-down” valve [4], the schematic of the CAD layout of the two-level microfluidic device and its two modes of operation. The two-step photolithography of the molds (Figure 3) using negative photoresists, SU8-2015 and KMPR1050, allows for the patterning of the multi-depth microfluidic mold without the need for additional passivation of the first resist layer, thereby simplifying fabrication. The mold can be reused to produce multiple devices; a photograph of the valve region of a used multi-depth mold is shown in Figure 4. Photographs of the device operating in different modes are shown in Figure 5.
The unique capability of this valved microfluidic biofilm reactor to section uniform biofilms can facilitate high-throughput biofilm studies, including new drug discovery. The push-down valve configuration allows for easy integration of electrodes for the study of alternative treatment methods like electric fields. Furthermore, the integration of the biofilm reactor with a real-time measurement system will enable high-throughput continuous analyses on uniform biofilms while ensuring tight and reliable controls.