Some good news for beachgoers who have worried about when they should reapply their sunscreen: A group of students from the University of Waterloo in Ontario has invented a marker that changes colour when sunscreen has lost its protective effects.

The invention is one of 20 finalists selected from hundreds of entries from around the world in the James Dyson Foundation annual awards.

The competition is open to students of product design, industrial design or engineering, or recent graduates, in 18 countries including Canada.

The competition selects one international winner, an international runner up, and a winner from each country.  Dyson released its 20 finalists in the international category late Wednesday night.

Here are some of the coolest inventions from the list of finalists. The winner is unveiled on Nov. 6.

Sunscreen warning marker

Suncayr is the brainchild of a team from the University of Waterloo “who are fed up with getting sunburned.” It’s a marker that changes colour when your sunscreen is no longer blocking UV rays.

“Painful and peeling sunburns greatly increase an individual’s risk of developing skin cancer, as well as making you look and feel miserable for far too long,” the team says in its proposal.

Users can draw whatever shape or design that they like on their skin, and then apply sunscreen over top.

When the sunscreen is still protecting the skin, the ink is one colour. When UV is able to get through and hits the ink, it changes to a second colour, meaning that it’s time to re-apply.

The marker lasts all day, does not cause a tan line and while water-resistant, it can be removed at the end of the day.

Self-filling water bottle

Fontus bottle one of year's coolest inventions

With the Fontus water bottle, cyclists won’t have to pack multiple bottles of water for long rides. The Fontus, an entry from Vienna student Kristof Retezar, is essentially a self-filling water bottle that is attached to the bike.

The solar-powered device collects moisture from the air, separates the water molecules from the air molecules and stores the liquid in the attached bottle. It can collect up to half a litre of water in about an hour in relatively humid conditions.

“The Earth’s atmosphere contains around 13.000 km3 of mostly unexploited freshwater,” the product’s description reads. “This project is an attempt to discover these resources.”

Good not only for long bicycle trips, the device may be a way to collect fresh, safe drinking water in parts of the world where water is scarce.

Broken net warning system

Remora system one of year's coolest inventions

Inventor Alejandro Plasencia of Spain points out that some 100 million tons of broken and abandoned fishing nets, what he calls “plastic soup,” float in the world’s oceans. These “ghost nets” pose an environmental hazard, as well as threaten ocean life.

Plasencia’s proposal is a four-part system called Remora that notifies fishermen when a net is broken, so it can be repaired in good time.

The system includes a net that biodegrades in four years, which is the average lifespan of a fishing net. Meanwhile, radio-frequency identification (RFID) tags are placed throughout the nets that can transmit data about damage to an RFID reader.

An app lets the fisherman track the damage and co-ordinate repairs with staff on land.

Portable incubator

MOM inflatable incubator up for invention award

U.K. inventor James Roberts writes in his proposal for MOM, an inflatable incubator, that an estimated 27,500 babies of the 150,000 born each year in refugee camps will die due to a lack of access to an incubator.

After watching a television report about the crisis of refugees fleeing Syria, Roberts was inspired to invent an inexpensive, electronically controlled, inflatable incubator that can easily be used in third-world settings.

The MOM can provide the same functions as regular incubators, such as a stable heat environment, humidification and a jaundice light, and can be easily collapsed and include in care packages that are already prepared for transport to refugee camps.

The electronic components can be operated without a main power source for more than 24 hours, and can be powered up by using available resources, such as a car battery.

While regular incubators cost tens of thousands of dollars, the MOM can be manufactured, tested and delivered to a site for about $500.

Rotting meat label

The Bump Mark up for invention award

The Bump Mark is a label that can more accurately predict when meat products that are sold in grocery stores are starting to go bad.

The label is essentially a small patch of gelatin, a protein that decays at about the same rate as other protein-based products, such as meat. As the gelatin breaks down the label gets bumpy, meaning the meat inside the packaging is likely no longer fresh.

Designer Solveiga Pakstaite of the U.K. says the Bump Mark “is able to tell you exactly the condition your food is in, simply by running your finger over the label. If it’s smooth, then you’re good to go, but if you start to feel bumps as the gelatin breaks down, be cautious.”

The label is better than the expiry date typically found on meat products, Pakstaite says, because it gives consumers information about the actual condition of the food.