The function of a research article introduction is threefold:

In other words, a good introduction arouses attention, leaves the reader with a good idea of what the article is about, and how the writer intends to develop the topic. We will tackle all three issues in the following pages.

It is recommendable to work on the introduction only after you have completed a first draft of your research article. This way you will find it easier to combine the three elements that make for a good first paragraph.