Robot doctors, a rocker-designed Mars rover, parenting lessons from snails - few scientific marvels escape the notice of Joe Palca, science correspondent for National Public Radio (NPR). This week he's in Tianjin, China, compering discussions on tech and physics - which is where we caught up with him to hear about his favourite stories of all time.

Here's Joe with his top five:

When you say "particle accelerator", most people think of a giant ring like the Large Hadron Collider straddling the border of France and Switzerland. But what if you miniaturize the process, shrinking the accelerator to a size where it would fit on a single silicon chip? That’s what scientists at Stanford University and the SLAC National Accelerator Laboratory are trying to do. If they pull it off, it would be possible to build desk-top devices for delivering medical therapy or probing the atomic structure of materials. The tricky bit is figuring out the physics of controlling individual electrons at atomic scales, but the researchers say they’re getting there.

You need a powerful radio transmitter and a giant radio antenna to send a signal from Mars to Earth, and even then the amount of data you can send is limited. So NASA is turning to a system like fiber optics on Earth, but using laser rather than fiber optic cables. They’ve already demonstrated the ability to send high definition video from as far away as the moon, and the agency is building a system that could work from Mars. Imagine a live broadcast of astronauts landing on Mars!

The researcher who invented the CMOS chip, the chip that allows you to use your cell phone as a high definition camera, has his sights on a new project. He’s invented a chip that can detect a single photon of light. There are devices now that can do that, but they require special manufacturing techniques and ultra-cold refrigeration in order to work. The new chip works at room temperature, and can be built with standard tools. One day these chips could be built into phone cameras or sensors, enabling them to detect things the human eye can’t see.

Engineering researchers at MIT have built a device that suck water out of the air, even in the driest desert on Earth. The device is solar powered, so it needs no external power supply. A special material called a Metal Oxide Framework draws moisture from the cooler nighttime air when the water content of the air goes up, and then the water it released with the material is heated up bu the sun during the day. Their demonstration model only produces a thimble full of water, but they’re hoping to scale up to a version that could provide drinking water for an entire family.

The flood of Syrian refugees has put a strain on German resources, but a team of scientists figure they can provide a crucial service to refugees while getting important data in the process. They are testing various methods of teaching German as a second language to see which ones work best, while using brain imaging to validate their findings. Traditionally, German language teachers start with a heavy dose of vocabulary, and only introduce sentence structure and syntax later on. The researchers are hoping to prove that the opposite order might be more effective.