"If getting a cape can make a child feel like they are a tiny superhero," she says, "I'll keep sending them for the rest of my life."
Rosenberger, 28, of Seattle launched Tiny Superheroes in January 2013, and along with her volunteers has sent over a thousand capes to ailing children across the world, including survivors of the Boston Marathon bombing and the Oklahoma tornadoes.
"They're all 'Super' and then their name," says Rosenberger, who recently left her job at a software company to pursue making capes full time. "So it would be 'Super Amelia' or 'Super Elliot.' "
Riveted by a blog on Brenna Westlake, a now 19-month-old little girl battling Harlequin ichthyosis, a rare skin disorder that covers her body with plates of thick skin that cracks and splits apart, Rosenberger says she felt she wanted to do something to honor the child's bravery.
Courtesy of Crystal Wright
She reached out to Brenna's parents through their blog.
"I said, 'We think your daughter is a superhero, and we would love to send her a superhero cape,' " she says.
Brenna's family was thrilled.
"They said, 'We've been calling her our superhero since she was born,' " she says, "so they loved it."
Crystal Wright, mother of one-year-old Amelia Wright, who has shaken baby syndrome says it was an instant hit.
Courtesy of Lia Tremblay
The cape lifted the spirits of Amelia's parents, Crystal and Nate, as well.
"When a family goes through something like this, every day is a nightmare or a roller coaster," she says. "Something like this means so much."
Lia Tremblay, mother of five-year-old Joe, who has a rare genetic syndrome and an intellectual disability, is another grateful mother.
"Joe loves his cape, and we love it, too, as his parents," says Tremblay, 38, of Colonial Heights, Va. "It's nice to have this little symbol to show everybody how strong and super we think he is."
Know a hero? Send suggestions to firstname.lastname@example.org. For more inspiring stories, read the latest issue of PEOPLE magazine