Abstract: The ±1 000 V polypropylene (PP) electrets were prepared by means of the corona charging method. To compare the skin microstructure after the application of electret at different time points，the changes in the skin structure were observed after the application of ±1 000 V PP electrets on rat abdominal skin with the inverted phase contrast microscope. The results indicate that both the positive and negative PP electrets can change the microstructure of rat skin and the changes in the skin structure are basically the same. Therefore, skin stratum corneum can fall off in varying degrees after the application of electret for a long time. Electret can be used in transdermal delivery formulation to reduce the barrier function of skin and increase the drug permeation through skin. Compared with +1 000 V PP electret, -1 000 V PP electret has the delaying effect for a shorter time. 

Key words: electret; transdermal; skin structure; time window