Agree that people like him should get more recognition, maybe even the Nobel Peace prize.

In reading the article, though, I don't think it took him 20 years to make it. Instead, I think it means he made a promise to do something about children dying from pneumonia and it took him 20 years to figure out how to do it. I base this on the following paragraphs in the article:

In 1996, Dr Mohammod Jobayer Chisti was working in the paediatric department of the Sylhet Medical College Hospital in Bangladesh. That evening he made a promise that he would do something to stop children dying from pneumonia.

When asked how he feels to be fulfilling that promise he made 20 years ago he replies: "I have no language to express this."

The article said the following:

After two decades of research, Dr Chisti has now come up with a low-cost device with the potential to save thousands of babies' lives.