To show the possibility of subsequent downstream detection (post-amperometry), the device design was altered to include a separate port for reagent addition and a channel for mixing and chemiluminescent detection of ATP (Figure 4A-B). A second input for reagent was added at a 90° angle to the channel and the output channel extended to form a mixing T and a reaction and detection channel. ATP detection occurred via the luciferin-luciferase assay as previously reported.22 (link) For this assay, 50 mg of crude firefly lanterns (Sigma-Aldrich, St Louis, MO) and 3.2 mg of D-luciferin (Gold Biotechnology, St. Louis, MO) were dissolved in 10 mL of PBS and sterile-filtered. A syringe pump was used to continuously pump reagent through the device at 15 μL/min. The multi-modal device was placed on top of a PMT (Hamamatsu Photonics, Shizuoka, Japan) in a light-excluding box.22 (link) Voltage from the PMT was monitored for ATP quantification. ATP (Sigma-Aldrich, St Louis, MO) and norepinephrine (Sigma-Aldrich, St Louis, MO) standards were made in PBS the day of use. Traces shown in Figure 4C were smoothed in PeakFit (San Jose, CA) with a small Savitzky-Golay filter (0.5% window) for presentation purposes (to help filter noise).