Pico-Injector for the Discrete Chemical Stimulation of Individual Cells with a High Temporal and Spatial Resolution

We present a new tool (Pico-Injector) for the discrete chemical stimulation of individual cells in their physiological environment. Key features are the precisely controlled release of two individually addressable substances in the lower picoliter (pL) range (V = 9 pL) with a high spatial (< 50 μm) and temporal (< 100 μs) resolution while avoid any diffusion-based leakage of the drugs. This is achieved by a disposable and biocompatible cap that is placed on top of a dispenser generating a phase-gap between dispensing agent and target liquid when the dispenser is dipped into the latter. For the phase-gap we have proven a long term stability of more than 30 hours against capillary priming and a maximum volume ejection rate of up to 220 nL/s.