Table 1.

External [${\mathrm{O}}_2$] in the air and cell culture media inside the miniature incubator used for the fluorescence lifetime imaging of actively respiring cells. The values are presented with the standard deviation obtained from four measurements.

[${\mathrm{O}}_2$]	20%	19%	16%	13%	10%	7%	4%	1%	0.5%
Air (mmHg)	$134.4\pm 3.5$	$132.0\pm 4.1$	$112.1\pm 6.1$	$94.4\pm 6.4$	$70.5\pm 1.3$	$50.1\pm 0.9$	$29.3\pm 2.5$	$8.3\pm 1.9$	$3.0\pm 0.5$
Cell media (mmHg)	$110.4\pm 7.2$	$108.1\pm 7.2$	$92.8\pm 11.1$	$86.9\pm 11.3$	$59.3\pm 11.2$	$36.5\pm 11.2$	$20.7\pm 5.9$	$5.6\pm 1.0$	$1.4\pm 0.5$
Cell layer (mmHg)	$89.5\pm 4.4$	$70.4\pm 4.8$	$56.5\pm 4.9$	$42.9\pm 6.1$	$33.3\pm 6.1$	$21.0\pm 7.5$	$10.3\pm 3.9$	$2.3\pm 0.8$	$0.6\pm 0.2$
Control media (mmHg)	$110\pm 4.8$	$108.8\pm 2.2$	$92.5\pm 3.4$	$89.5\pm 4.4$	$61.8\pm 3.4$	$37.6\pm 1.9$	$20.7\pm 2.0$	$5.9\pm 0.5$	$1.4\pm 0.4$

Note: Cell media: The probe was inserted in the media $\sim 1\mathrm{mm}$ below the top surface.

Cell layer: The bottom of Lab-Tek Petri dish, where the cells are adhered.

Control media: [${\mathrm{O}}_2$] in the media without the cells.