You could either heat the cells until they burst. You could add some chemicals/enzymes that will destroy the proteins that hold the cells together and so it will break open. Or you could add chemicals such as an alkali followed by an acid which will also break the cell open.
When trying to decide which method to use on my device I need to bear in mind will this be simple and safe to manufacture and use and will it work on my device. Just because something works in a tube doesn’t mean it will work in the environment of my device.
I will have to try a few things out but my hypothesis (theory) is that alkali and acid will be the best method. I don’t need any heaters for this. I just need to add the 2 chemicals to my cell. The chemicals will be at a low concentration so shouldn’t be dangerous. Hopefully it should be quite a quick process too. Most importantly it won’t damage the DNA inside my cell and it won’t damage the chemicals I use to copy my DNA as the alkali will be neutralised to water by adding the acid before I add any more chemicals.