Sometimes your subscribers can miss your latest campaign and not open it. In this case, it can be useful to re-send the campaign to these subscribers. For this purpose, you can create a segment based on a campaign.
To create a segment for the subscribers who haven't opened a campaign follow the steps below. For a more detailed explanation of the first steps check the article Create a Segment Based on a Campaign
Start by going to the segments section and click on Create New Segment.
Name your segment and under Email Campaigns, select the campaign upon which you would like to base the segment. The segment will only look at the recipients of this particular campaign.
Now, under Activity-based filter, choose not opened condition. Leave the subscriber-based filter as it is.
When you're done, click the Create button.
Now you have a segment of the subscribers who haven't opened the campaign. You can create a duplicate of this campaign and change the recipient list to only this segment. If needed, you can repeat the process with the duplicated campaign as well.