In the 1960s Dr Voegeli asked General Electric and AT&T to make an electrical heating device that would be more convenient than warm water in a bucket, but they weren't interested: link.

We have built and successfully tested such a device:

USB heating cup

And this is the type of USB microscope you can use, from the comfort of your own home:

And this is what you can see with it. Before, during, and after heating for 3 weeks:

Before heating: many sperm During heating: less After heating: almost none

If you get a laboratory semen analysis, they'll consider you sterile if there are less than 1 million sperm per milliliter: link.