Paul Skarstad was a pioneering scientist at Medtronic who helped shrink the size of pacemakers and other medical devices by designing smaller, more powerful batteries that last much longer than their predecessors.

As a result of Skarstad's groundbreaking research, the devices are now more reliable and comfortable to wear, and people can go as long as 15 years before needing a new one — a big improvement over the 1970s, when Skarstad joined what is now the world's largest medical device company.

Skarstad, who retired from Medtronic in 2006, died May 15 from a heart attack while relaxing on the sofa at his Plymouth home of more than 40 years. He was 74.

"He was a really important person at Medtronic," said Darrel Untereker, Medtronic's vice president of technology. "Paul was the first to prove that a lot of things could be done. ... Paul was a scientist's scientist. He set standards for scientific rigor that are still in place today."

Born in Grafton, N.D., Skarstad spent his teenage years working on the family farm and exploring the nearby countryside. He collected everything from rocks to butterflies, displaying an unquenchable curiosity that drove him throughout his life.

He studied chemistry at the University of Minnesota, where he met the woman who would become his wife. Both were in the orchestra.

"He played the violin, and I played the flute," Marna Skarstad said. "Music was a theme for our whole life."

After getting his Ph.D. in chemistry from Cornell University in 1972, Skarstad worked at the U.S. National Bureau of Standards for one year. He joined Medtronic in 1976.

Skarstad's first major discoveries allowed Medtronic to increase the amount of current a medical device could draw from a battery, which was fairly limited at the time, colleagues recalled. He later developed the first power source for implantable defibrillators, which send a dose of electric current to the heart to correct abnormal rhythms.

Altogether, Skarstad and his research team collected 19 patents for their work, according to the U.S. Patent and Trademark Office. In his 30 years at Medtronic, Skarstad worked his way up through management and retired as senior director of energy systems, where he oversaw research and development on batteries and other power sources.

Colleagues say Skarstad was a demanding boss who pushed people to do their best, but at the same time was quick with a self-deprecating story to lighten the mood. He loved it when co-workers played pranks on him.

"He was a pretty awesome mentor," said Medtronic manager Craig Schmidt, who worked with Skarstad for 17 years. "The first report I did for him underwent 21 revisions — my Ph.D. thesis underwent three revisions."

Beyond his scientific pursuits, Skarstad was an adventurer who kayaked around the glaciers of Greenland and bicycled through the fjords of Norway. After he was diagnosed with Parkinson's two years ago, he designed a training regimen that allowed him to continue bicycling 28 miles per day while still keeping his heart rate below 120 beats per minutes, as required by his doctor.

"He had a strong tremor in his right hand, but he didn't let that stop him," said Marna, who celebrated her 50th anniversary with Paul last August. "He loved the outdoors."

In addition to his wife, Skarstad is survived by a son, Erik Skarstad; a daughter, Alida Skarstad Fischbach; five grandchildren and other close family members and friends. A memorial service will be held Saturday, at St. Philip the Deacon Lutheran Church, 17205 County Road 6 in Plymouth. Visitation will begin at 10 a.m.