Monitoring the surface tension of lipid membranes by a bubble method

A new method for the determination of lipid membrane surface tension was developed. Advantages of this method are that it allows for multiple measurements on a single membrane, is fast and direct not requiring empirical corrections, may be applied for dynamical surface-tension measurements and may be used with thin films and asymmetrical electrolytes. The pressure and radius of a bubble are measured. A piezoresistive sensor is used to minimize the transducer compliance. By moulding the sensor to a brass plate a resolution of 0.025 mm H2O (0.25 Pa) is obtained. The bubble is filmed using a videocamera and the radius of the bubble determined with the aid of a microcomputer. Data for monoolein/hexadecane in potassium chloride solutions and a cooling curve are presented and compared with previous results.