FORT WORTH -- Nine-year-old Christopher Sanchez held out his arm to a nurse in an exam room at Cook Children's Medical Center.

"This arm," she said. "Perfect. Thank you."

Christopher knows the drill. He gets tagged, poked, and jabbed a lot.

This time, he's in for a painful muscle biopsy.

"It was time to go to the doctor. He had tears in his eyes," said his mom, Jessica Sanchez. "But once we told him he was going to play with the rover again, he got super excited."

Nurses call it the "rover" because they don't know what else to call it.

It's a new multi-sensory, de-stressing gizmo -- several gizmos, actually, attached to a rolling cart.

There's a glass cylinder of bubbling water that changes color, as well as a long ponytail of color-changing fiber optic cables. Rover plays music and projects whirling images on the wall.

It looks like something Wile E. Coyote would build.

Christopher controls the colors by turning a pillow-sized cube or pressing big buttons on a panel.

"I want red," he says repeatedly.

Christopher has autism. He's happiest when he can turn his world red. He wears a red Texas Rangers hat, red T-shirt, and red sneakers. His eyes grow wide in rover's red glow.

Cook's workers had been looking for something to help calm kids down, especially the increasing number of kids they see with autism.

They found the multi-sensory, anti-anxiety cart in a catalog for $7,000. A donor bought it.

"I have nurses who'll call me and say, 'Betsy, this child's blood pressure is really high. His heart rate is really high,'" said child life specialist Betsy Hillyard. "We bring rover in, and you can just see physically, their face calms. Their muscles start to relax."

They do about 90,000 surgeries a year at Cook Children's. They have just one rover. They have another on order.

But what they're finding out is they could use a lot of rovers.

"He fell in love with the lights and bubbles," Jessica Sanchez said. "This is like a miracle worker."

His mom said this is the first time Christopher actually wanted to come to the doctor.

If he has to be in the hospital, at least he can call the shots.