A patent gives you a monopoly which makes things easy.
You occasionally search the market for products that contain your tech (in this case eink), then look in your records to see if they bought/licensed from you.
But is it that infringement can be proven only by a court? So can US customs do any thing in such cases, even if we assume they have the competency to judge if a particular import violates IP.
They file a case, and ask for a preliminary injunction. And once that's granted (which is likely), they take that order to customs, and customs will start looking for those devices in shipments from your supplier or to you.
