A speaker whizzing around the lecture hall on a personal transporter, a robot bumping into audience members’ feet, free donuts — this scene may not be like a typical lecture on Science Hill. But at “Science Saturdays,” it is by no means out of place.

A concept pioneered by mechanical engineering professor Ainissa Ramirez in 2004, “Science Saturdays” bring the research passions of Yale faculty members to the New Haven community through a series of lectures and hands-on demonstrations. This past Saturday, mechanical engineering professor John Morrell spoke to over 180 adults and children, grades seven and higher, about the process of developing a novel invention that exploits the concept of balance: the Segway Personal Transporter.

Morrell, who spent the entire lecture balanced on the Segway, said he thinks the events challenge notions of scientists as people who work hard without having fun. Helping to invent the personal transporter while employed at Segway Inc. before coming to teach at Yale was “incredibly exciting,” he said.

“Engineers are humans, too,” he said. “Most people don’t look to engineering to get that sense of group excitement. That joy of creating something from nothing can definitely happen in a technical environment.”

Indeed, interactive demonstration tables — complete with color-changing materials sensitive to UV rays and shape-memory alloys that bounced back into their original shape when heated — injected an element of playfulness into the day’s events, which culminated in a raffle that gave away a free iPod Shuffle.

Shattering stereotypes about science is a broader goal of the lecture series, Ramirez said.

“Science Saturdays” aim to deconstruct the image of the “typical scientist” and encourage students to appreciate the diversity of the field, she explained.

“It’s not just the stale pale male who’s doing science,” she said. “We have people of all different shapes and sizes and colors and interests.”

When introducing the speaker, Ramirez drew in the audience by drawing a connection between Morrell’s interest in cycling and the content of his research: wheels, robots and balance machines.

But the audience members, initially slow to abandon the snack tables, were already enthralled by the robot Morrell had set loose around the lecture hall and the large, wheeled scooters — which Morrell later explained were Segways — leaning against the blackboard.

Morrell began his lecture by explaining that the concept of a Segway originally came from a desire to create more affordable and easier-to-use wheelchairs for the physically disabled, but over its development period, the vehicle became much larger in scope.

The audience of the Segway now draws from a broad cross section: from police officer to recreational polo players to characters at Disney theme parks.

“We certainly didn’t expect to make it onto Frasier!” Morrell exclaimed, pointing to a picture of Dr. Frasier Crane, from the eponymous sitcom, riding on the device.

The Segway — a vertical, two-wheeled self-balancing transportation device — works by using gyroscopic sensors that detect the tilting of the machine forward or sideways and issue a command to the wheels to spin in order to bring the machine back into balance, Morrell said.

Before it was released, many thought the Segway would become the favored form of transportation across small distances because of its small perimeter and its use of a “green” lithium-ion battery. But the advanced hype about the project was, at times, overblown, he said.

“People were saying, ‘This is going to change the world,’ ” Morrell said. “It’s hard to live up to that.”

While the device did not quite live up to buzz when it was unveiled on “Good Morning America” in 2001, Morrell said inventions like the Segway are usually slow to catch on because they require a change in people’s behavior.

Tinkering around to get all the parts working right took just over four years, he said.

Segway Inc. engineers had to perfect minute details about the device before it was released, Morrell explained. For instance, they looked into creating a “bi-wire system” of redundancy by which two balancing systems, instead of just one, were used to drive the machine, as well as into coordinating the frequencies of the gearboxes to achieve a pleasant sound.

Kinematics also played a role in the design. Because the machine has a high center of gravity, Morell said, it can ride up steep inclines and turn in place. Segway’s makers also had to think about what would happen if a user leaned too far forward. They compensated by implementing a mechanism whereby the wheels would speed up.

“We fell down a lot before we figured stuff out,” Morrell admitted with a laugh.

At the end of all of it, “we felt like test pilots,” Morrell said, switching back and forth between a picture of the design team and one of posing astronauts in uniform.

Audience members lingered after the lecture to take turns riding the Segway up and down the hall and to ask Morell more in-depth questions about its mechanics, while others stayed to try their hand at some more of the demonstrations outside.

Ramirez said community interest in the lecture series has been unprecedented. When it was started, Ramirez said she anticipated no more than 50 attendees, but some of the more popular lectures draw over 250, she said. In its fifth year running, the events now draw a diverse group of core members who return time after time.

Erin Lavik, co-host of “Science Saturdays” and a biomedical engineering professor, said the lectures give scientists who are good at communicating about their research the chance to convey how they “go about knowing what they know.”

“I think the most important thing it does for the audience is it exposes them to scientists and the kinds of questions they ask and how they ask those questions,” she said.

The goal of educating the lay public, Ramirez said, is key in a world that is becoming increasingly technologically advanced — in which knowledge will ensure continued participatory democracy.

Drawing students into the often technical and jargonistic science that Yale researchers are carrying out can be difficult, she said, but it is aptly captured by the “the three Ds”:

“Dynamic lectures, demonstrations — and donuts!”