DISSOLUTION OF AIR BUBBLES BY THE RESISTIVE PULSE AND THE PRESSURE REVERSAL TECHNIQUE

The resistive pulse technique has been used to study the dissolution of single air bubbles in a sucrose/NaCl solution. A novel technique has been developed, which extends the uses of the resistive pulse technique to single particle dynamics. Observed bubble diameters have been in the range from 22 to 3 μm. By pressure drive, a bubble enters a current-carrying pore and increase in resistance proportional to the particle volume is detected. When the bubble exits the pore, the pressure can be reversed so that the bubble is captured flowing back and forth through the pore. The time the bubble spends outside the pore between reversals may be more than 100 times longer than the particle transit time through the pore. Thus, the bubble spends practically all its time outside the pore. Changes in the bubble volume may be measured very accurately in a size range previously not easily accessible for observations of single bubbles. The effect of surface tension is observed and the measurements are consistent with theory. The rates of dissolution with and without proteins (BSA) present in the sucrose/NaCl solution are compared and it is evident that proteins have a drastic effect on the apparent rate of dissolution, slowing it dramatically as the bubbles dissolve. © 1990.