How stuff works

We use them every day – on our smartphones and tablets, at the supermarket, in our cars, and even at the gym. But have you ever stopped to wonder about how touchscreens work?

Engineering, Computer and Mathematical Sciences professor at AUT Fakhrul Alam has. In fact, he’s currently harnessing touchscreen principles to develop a smart floor which could make life safer for the elderly by tracking them walking and detecting any falls.

“When you look at your smartphone, the first layer you see is the glass protector, and behind that is the display. Between the glass and the display, there is a ‘digitiser’ made up of many tiny capacitive sensors. It’s basically a glass-like layer coated on both sides with a transparent conductive material, usually indium tin oxide (ITO),” Fakhrul explains.

“On one side, tiny metallic lines are painted horizontally, and on the other side, they’re painted vertically. Every time the lines cross, an electric field is generated between them creating a ‘capacitor’, and this field is constantly being monitored by the device.

“When your finger gets close to, or touches, one of the capacitors it disrupts the electric field, changing the value of the capacitance. The location of the disrupted capacitor on the grid is recognised by the processor (essentially the brain behind the touchscreen) which has also been programmed to figure out what you want it to do. Depending on the gesture (double or single tapping, or pinching to zoom) it will respond to your command accordingly.”

These days capacitive screens are the most common and sophisticated type of touchscreen, but there are others, too. ATMs and kiosks, for example, need to be more robust and require you to push down on the screen with your finger before a signal is sent. This resistive touchscreen technology consists of two thin layers with a small gap in between. When you press down, the layers touch, creating an electrical connection and sending a command to the device. If you don’t push hard enough, it won’t work.

As technology evolves, touchscreens are becoming more advanced, and touchscreen principles are being harnessed for an ever-growing lineup of products.

Story by Vanessa Trethewey. Photo by Tony Nyberg.

Tried and tested by billions of sheep, wool is nature’s coolest multitasker. Not only does it keep us cosy in the winter, but it also keeps us cool in the summer making it the ultimate all-season survival kit.

But how does it work? General Manager of Campaign For Wool NZ, Kara Biggs, is asked this question a lot.

“There are a few things at play which means wool becomes nature’s own little climate control system,” she explains. “First, wool has natural crimp – or waves – in the fibre, which trap millions of small air pockets. These mini air pockets heat up and retain warmth in winter.

“Meanwhile when it’s warm, wool absorbs moisture vapour (like sweat) from the body and releases it into the air which cools the body through evaporation. Wool can absorb up to 30% of its weight in moisture vapour without feeling damp, allowing your skin to breathe which makes you feel more comfortable.”

Compare that to synthetic fibres which Kara says are plastic and trap moisture, making you feel wet, sticky and hot.

Although all wool has temperature regulating attributes, certain breeds are better for certain applications.

“Merino is a fine wool breed and works well next to the skin because the cuticle (outside layer) of the fibre feels softer. Strong wool breeds like Romney, Perendale and Coopworth make up about 80% of New Zealand’s wool production and are better suited to upholstery, carpets, insulation, bedding, furnishings and soundproofing applications, because these need a heavier, more robust fibre that is more durable.”

Story by Vanessa Trethewey.

Carbon molecules are in a constant process of exchange everywhere around us.

Principal Scientist – Carbon Cycle at Earth Sciences New Zealand Jocelyn Turnbull studies carbon movement and concentrations, and the imprint that we humans leave on this cycle.

She explains that carbon dioxide (CO2) molecules occur naturally in the atmosphere and are constantly on the move. The basic elements of carbon cycle transfer include plants and trees, which take in CO2 during photosynthesis, and use it to grow, storing it in their roots and the soil. The carbon is then released when they rot or decay.

Humans and other animals release carbon when they breathe and when they decompose. Oceans act as natural carbon reservoirs; as CO2 increases in the atmosphere, the oceans absorb more of that CO2. Rocks and other geological deposits have the capacity to store carbon for millions of years, but only exchange it slowly with CO2 in the atmosphere.

“At any given time, there’s enormous amounts of carbon exchanging out of the atmosphere and then back into the atmosphere. We describe that as the Earth breathing. You see the same kind of thing happening with the ocean. The ocean absorbs a whole lot of carbon dioxide and also releases a lot of it. That’s happening all the time in a natural system and, on average, over a year, over a decade, that’ll be in balance.”

The dynamics of ocean movement play a big role in how much carbon the ocean takes in. “It’s complicated because the ocean is not like a nice, well-mixed glass of water. It’s only at the ocean surface that exchange can happen, which means the atmospheric exchange of carbon with the ocean can take thousands of years.”

On land, the amount of carbon that is retained in the soil and the rate at which it is released, is also complex and determined by things like temperature and precipitation, and the type of vegetation present.

Humans tilt the natural balance of the carbon cycle by burning fossil fuels (such as oil, coal and natural gas), which are transformed into CO2 in our atmosphere.

“We tend to get a bit myopic and look at planting trees as a great way to reduce global warming, but the carbon is not actually being locked into those trees indefinitely. If you chop the trees down and burn them, or in the case of forest fires, carbon goes straight back into the atmosphere.”

Jocelyn says that in New Zealand, vehicle emissions are the number one culprit for human-made CO2 emissions by quite a long shot. “We also produce CO2 from electricity generation, but not much, because most of our electricity comes from renewable sources. We really want to understand where CO2 emissions are coming from and how we can reduce them, so through our research programme, CarbonWatch-Urban, we’re working to map where and when those emissions occur around New Zealand.”

Thanks to internationally groundbreaking research first begun in New Zealand by scientists Athol Rafter and Gordon Fergusson, who began measuring atmospheric CO2 in 1954, Jocelyn and her team are able to measure radiocarbon isotopes in our atmosphere. This allows them to distinguish human-made sources and concentrations of CO2 in our environment from those that are naturally occurring.

Too much carbon in our atmosphere fuels global warming; too little of this element and the Earth would begin to cool.

Story and photo by Nicola Edmonds.

Māori celestial navigation is a wayfinding system that relies on careful observation of the natural world rather than instruments, explains Kaupapa Māori Coordinator at Stardome Observatory & Planetarium Olive Karena-Lockyer. She says tohunga whakatere (navigators) used the following natural observations:

• Stars and star lines – Specific stars and constellations (such as Matariki/Pleiades) were memorised as rising and setting points on the horizon, forming ‘star paths to steer by at night.          
• Sun and moon – The sun’s path during the day and the moon’s phases and position at night helped track direction and time.    
• Ocean swells – Patterns of waves and currents indicated where islands lay beyond the horizon.           
• Birds and wildlife – Seasonal movements of seabirds, fish and other animals gave clues to nearby land.   
• Clouds and colours – Cloud shapes and reflections on the ocean surface often revealed land just out of sight.

“By combining these cues, Māori navigators could travel vast distances across Te Moana-nui-a-Kiwa (the Pacific Ocean), guiding their waka hourua (double-hulled canoes) to Aotearoa and beyond,” Olive says.

Story by Monica Tischler.

You may take for granted your phone magically charging when you place it down in the centre console of your car – but it’s not sorcery, it’s science.

Induction charging primarily uses two coils of wire to create an electromagnetic field that enables energy transfer between two devices. When power passes through the transmitter coil in the base of the charging pad, it conjures an invisible bubble of energy, known as an electromagnetic field. Your phone has a similar receiving coil that, when placed inside the electromagnetic sphere, induces an electric current which the phone converts into power to charge its battery.

Think of the process as an invisible handshake between the coil in the charging pad and the one in the phone. Both coils know exactly what to do; charging begins the moment your phone comes into contact with the charging pad.

While the technology required for wireless phone charging is relatively new, the concept of induction charging has been around for over a century; Nikola Tesla first explored the idea of power transfer back in the late 1800s.

Story by Ryan Bos.

When you’re stopped at traffic lights, waiting for them to turn green, do you wonder who or what is in charge of them?

According to Kipi Wallbridge-Paea, Optimisation Delivery Team Leader and traffic light expert at Auckland Transport Operation Centre (ATOC), the answer is a blend of humans and technology.

At the heart of the system is the length of time, or phase, that a green light stays green. Kipi explains initial settings for each crossing are established by traffic engineers. The settings form a base plan, which enables the system to run and adapt autonomously in real time. Engineers also set guidelines for real-time operations teams who act as first responders to unusual traffic conditions and can override the base settings to resolve problems with the network.

Beside each traffic signal, electromagnetic sensors are placed beneath the road surface just before an intersection’s white stop lines. They detect when a vehicle is waiting for the lights to change, though only when vehicles are directly above them.

Above ground, you’ll spot a cabinet nearby. It contains the brains of the corresponding traffic lights for that crossing or intersection. Information from the traffic sensors and pedestrian and cyclist crossing pushbuttons is fed into the control box, via underground wiring, to determine when each light turns green and the length of the phase. Every sensor in the wider network provides information on the direction and volume of traffic detected, allowing the system to dynamically adjust the traffic signal phases.

Because most traffic lights are in urban locations rather than state highways, regional councils tend to manage lights on local roads, while on-ramp signals on urban motorways are overseen by New Zealand Transport Agency Waka Kotahi.

The timing of traffic signals prioritises main arterial roads – a main road will have longer green light phases than those on a quieter side road. In regularly busy zones, individual lights are preset to synchronise with each other at peak hours to keep traffic moving. At night, or during quieter times during the day, the chance of consecutive red lights is greater because the traffic lights are set to operate independently.

If traffic lights stop working, it’s usually due to a faulty sensor; road works damaging a road surface are a common culprit. Until the lights are working again, normal give-way rules apply.

Story by Nicola Edmonds. Photo by Mark Smith.

To understand how sunscreen protects our skin, we first need to know why we get sunburnt, says Dr Chris Larsen, a senior lecturer of chemical sciences at the University of Auckland.

“One way of thinking about light is that it’s a form of energy,” Chris says. “The sun produces light at lots of different energies – we call that the solar spectrum. Most of it is the light we can see, the red, green, blue colours that appear white overall, but there are also other wavelengths like infrared, which is the low-energy light, and at the other end we have the high-energy ultraviolet light.

“Most ultraviolet light is absorbed by the atmosphere, otherwise we’d all burn to a crisp, but there are certain wavelengths that do get through.”

While UV doesn’t penetrate very deeply into the skin, its high intensity means that it still damages our cells. To prevent this damage, we protect ourselves with clothing and, of course, sunscreen. But how does the topical application of a cream stop high-energy light?

There are two different types of sunscreen, Chris explains.

“There is the thick zinc oxide or titanium dioxide version that you’ll see cricketers wearing with their very white faces. These work by particles reflecting or scattering the light. Titanium dioxide is also commonly used as the base for paint – so, with these sunscreens you’re literally putting paint on your face.”

The other type of sunscreen is slightly more complicated, chemically speaking, as it uses molecules to absorb light.

“This more common type of sunscreen uses organic molecules that absorb ultraviolet light due to the nature of their electronic structure,” Chris says. “Most sunscreen formulations use about 10 to 15 active ingredients, all of which are absorbing light.

“The different organic molecules absorb different UV frequencies, and then convert that light to another form of energy – typically heat.”

So, if you’re wearing sunscreen, do you feel warmer? It’s hard to tell, Chris says, because the same process that’s happening with the molecules in the sunscreen is simultaneously happening with the molecules in your skin and warming you up.

The reason sunscreen is comprised from multiple active ingredients is because they all have different jobs.

“It’s important to have a mix of different molecules that absorb different regions of light and at different amounts,” Chris explains. “Some are very good absorbers but have low stability. Others are not so good at absorbing but are very stable. So, by making a mixture of those you get the best of everything.”

Photo by Jo Percival.