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. Author manuscript; available in PMC: 2015 Feb 25.
Published in final edited form as: Adv Healthc Mater. 2013 Mar 12;2(9):1224–1228. doi: 10.1002/adhm.201200380

Figure 3. System validation.

Figure 3

(a) S. aureus was labeled using vancomycin (vanc)-TCO and fluorescent MNP-Tz. The Hall voltage distribution, as measured by the μHall device, qualitatively matched with measurements by flow cytometry (inset). (b) The μHall was used to count bacteria over wide dynamic ranges. Data are displayed as means ± SEM of triplicate measurements. (c) S. aureus could be detected in the presence of excess unbound MNPs. Indeed, the measured signals were comparable to those from MNP-washed samples. (d) The μHall sensor was used to detect Gram-positive bacteria. A panel of bacterial samples were labeled with vanc-TCO and fluorescent MNP-Tz. All Gram-positive bacteria (S. aureus, E. faecalis, M. luteus) showed high VH values, whereas the VH for Gram-negative species (P. aeruginosa, M. catarrhalis, K. pneumoniae) was < 20 mV (dotted line). These μHall results showed good agreement with flow cytometry data. The μHall data is displayed as mean ± SEM of 5000 VH values.