Bioluminescence Verification for Droplets Mixing Device Using Electro-Conjugate Fluid

Kobayashi, Kiho ;   Takemura, Kenjiro ;   Yokota, Shinichi ;   Edamura, Kazuya

Our previous study proposed a mixing device for droplet ┬ÁTAS using an electro-conjugate fluid. An ECF is a type of functional fluid that produces a jet flow under a non-uniform electric field. We used this attractive fluid to generate a rotational flow in a tiny cylindrical chamber. When multiple droplets are dripped into the rotational flow of the ECF, they may be subjected to the centripetal force due to the difference in density between droplets and ECF, resulting in droplets move to the center of the chamber and mix with each other. In this paper, we verify the suitability of the device by using luciferin-luciferase bioluminescence reaction. We observed the luminescence produced by mixing droplets of luciferin and luciferase using the device, and measured its luminance maxima to check droplets? mixing degree. In addition, we conducted two other experiments ('without ECF' and 'with still ECF') to compare with the experiment using our device('with the rotational flow of the ECF'). Results confirm there is no difference among them. Moreover, because the enzyme luciferase can be deactivated by surrounding environments, luminance maxima can also gauge whether the electric and centrifuging fields have any harmful influence on biological samples or not. From the results, it can be concluded that the influence of electric and centrifuging fields generated in our device might be negligible for biological applications.