Most articles indexed in PubMed are tagged with MeSH (Medical Subject Heading) terms, which can allow you to focus in on a particular topic with high precision. Chances are, there is a MeSH Term for the technique you are searching.
From PubMed, select MeSH from the dropdown list next to the search field:
and enter your term.
You can then navigate through the MeSH hierarchy to select the term that best fits your needs. Clicking on a broader topic (for example, Genetic Techniques) will allow you to browse through other related terms.
You might consider selecting the term as a major topic, which will limit material to that which is primarily about the subject. You also may want to specify a subheading, such as methods or instrumentation.
Clicking "Add to Search Builder" on the right will automatically formulate your search: