Electrostatic droplet generation for encapsulation of somatic tissue: Assessment of high-voltage power supply

The production of alginate microbeads with and without somatic tissue was investigated using an electrostatic droplet generator with a custom-made fixed (5.7 kV) and variable (0-20 kV) high-voltage power supply. The effects of applied potential, needle size, and alginate concentration were assessed as well as the immobilization of carnation callus cells. The high-voltage output from the power supply depended on whether the low-voltage input was increasing or decreasing. This hysteresis effect may be due to the electrical properties of the oscillator in the high-voltage source. While a short electrode distance and a high needle gauge were important for producing small alginate bead diameters (e.g., 100 mu m), alginate concentration in the range 1-3% (w/v) was not a key factor. Somatic tissue encapsulated using 2% sodium alginate retained viability over a 2-month culture period.