Among the indignities suffered by pregnant women are the clunky straps belted around the belly to measure contractions and fetal heart rate, tethered by wire to an electronic monitor.

What woman would not prefer a soft, stretchy, wireless alternative called the Belly Band?

Check it out in a Drexel University lab on Sunday.

Or if pregnancy is not your thing, head outside to Smith Playground to shoot off Alka-Seltzer rockets and meet the soap-bubble monster.

Still no good? Learn to make sauerkraut and yogurt at Di Bruno Bros. Hang with a dude named Dr. Skateboard. Hear the latest tricks to ward off hangovers. Sharpen your math skills at the poker table. Gaze at the stars.

There is surely something to intrigue anyone with a curious mind at the fourth annual citywide Philadelphia Science Festival, a nine-day extravaganza that starts Friday. Led by the Franklin Institute with the help of dozens of universities, museums, and businesses, the festival consists of 107 events - in restaurants and libraries, on rooftops and sidewalks, even at one cemetery.

The kickoff event, at 11 Friday morning, is an attempt by Drexel engineering students to beat the record for the world's largest Rube Goldberg machine. Pulleys, levers, ramps, and toppling dominoes - any kind of mechanical device is fair game in the atrium of the university's Bossone Research Center, on Market Street between 31st and 32d.

The festival continues Friday night at the Franklin Institute with an adults-only science-themed party. Among other attractions is the festival beer, brewed by Yards. Groaner alert: It's called Cerebral Pourtex. (Reservation and $15 ticket required; $10 for museum members.)

The Smith Playground event, with the Alka-Seltzer rockets and soap bubbles, is called Mess Fest and is slated for noon on Sunday.

"That's going to be ridiculous," festival director Gerri Trooskin said.

At Mess Fest, children also can make their own slime and take it home. No ticket required; pay what you wish.

Also at noon on Sunday, New York artist Eve Mosher will lead a community effort to draw a four-mile chalk line on the pavement through Kensington, Fishtown, and Port Richmond. The line roughly represents 10 feet above sea level, meant to show where stormwater could reach in the event of continued sea-level rise caused by global warming.

"It's a great way to have a conversation about a really complicated topic," said Mosher, who has led similar efforts in Miami and New York.

The line drawing begins at the Target store at 2701 Castor Ave. and ends in Penn Treaty Park. The event is free, but a reservation is requested at Related activities and food are available after at the Big Green Block, at 1800 Blair St.

Earlier Sunday, at 10:30, Drexel opens its ExCITe Center to the public to show off the Belly Band and other "wearable technology," at 3401 Market St. The wearable tech is woven at the center's Shima Seiki Haute Technology Laboratory, with computerized knitting machines that can shift seamlessly among up to 20 types of yarn - including one surprisingly soft variety made of stainless steel.

"You'd never know that's metal," said Kristy Jost, a Ph.D. candidate in materials science, displaying the yarn to a visitor recently. "It almost feels like silk."

The steel yarn is used to make garments that can store electric charge, which could be used to power sensors to monitor your heart rate or body temperature, lab director Genevieve Dion said. The garment would harvest unused, leftover energy from WiFi networks.

"We want to be scavengers of energy," Dion said.

At 2 p.m. Sunday, Bill Robertson, also known as Dr. Skateboard, will use the wheeled device to teach Newton's laws of motion.

Robertson, an associate professor who teaches science education at the University of Texas, El Paso, will lead the free event at Paine's Park, at Martin Luther King Jr. Drive and Benjamin Franklin Parkway.

Among festival attractions later in the week is "Playing With Numbers: How Math Can Help You Win," at 6 p.m. Wednesday at Rembrandt's restaurant and bar, 741 N. 23d St. ($5 admission). Al Bruno, a science interpreter at the Franklin Institute, will help patrons use probability to gain an edge at the poker and blackjack tables and in board games such as Scrabble and Battleship.

At 6 p.m. Thursday, check out the do-it-yourself fermentation event at Di Bruno Bros.' 1730 Chestnut St. location. Visitors can learn about the role of bacteria in making yogurt and sauerkraut, and will get to make their own.

A $15 ticket is required; reserve online - again, at

And if you miss Alka-Seltzer rockets the first time around, go to the festival's final event on May 3 - the all-day science carnival on the Parkway, with 150 exhibitors.

It starts at 10 a.m. The plan is to set off 5,000 Alka-Seltzer rockets at once, Trooskin said.

Is it science? Or fun? Sounds like both.