Tag Archives: sensor

What are sensors, how they work, and why they’re everywhere

A sensor is any device that measures an event or change in an environment and transforms it into an electronic signal that can be read and computed.

For instance, a sensor can take in physical parameters such as humidity, speed, or temperature (to name just a few), and make that data readable by a computer or other device. It takes an “input”, which can be almost anything, and converts it into an “output” that our electronics can understand. Or to put it in a different way, a sensor can detect an aspect of the physical environment and turn it into useful information.

Image credits: Jorge Ramirez.

Sensors, sensors everywhere — now also in XS size

We live in a world of sensors. From the tactile elevator buttons to the thermometers in our homes, they’re everywhere. Our smartphones, for instance, are equipped with an array of performant sensors. Whenever you fly a plane, there’s a whole arsenal there, telling the pilot everything about air pressure, speed, tilt, anything that can really help fly the plane.

Look around you (even ignoring the device you’re reading this on): how many sensors can you see around you?

At first glance, you may think there’s not too many. But look deeper. Are you in a car, or are there cars around you? Obviously, cars have a flurry of sensors, even the older ones. Public transit in many places is equipped with sensors. The thermostat inside the building — you’ve guessed it, also a sensor. In fact, it’s probably safe to say that unless you’re reading this while camping in the middle of nowhere, you’re probably surrounded by sensors that you don’t even notice.

It wasn’t always like this. Sensors used to be large, bulky, and expensive. Now, they’re small and easy to carry around. Researchers and engineers aren’t just looking at how well the sensor works — they’re looking at its energy consumption, necessary materials, sturdiness, and cost. Micro and nanotechnology and novel materials are making sensors smaller, smarter, and more adapted. As a result, we’re seeing sensors being applied in many new and exciting fields. For instance, some sensors can now be used as medical devices, either as wearables (for detecting things like glucose or insulin levels) or even inside the human body.

But before we get too carried away, let’s look at how sensors actually work.

How sensors work

A digital pressure sensor.

You first start with something that you want to sense — the quantity you’re measuring. The human body, for instance, is great at sensing light (with our eyes), smells (with our nose), and tastes (with our mouth). In essence, our body is equipped with a set of sensors, but each carries out a specific task.

Similarly, if you want to build an electronic sensor, you first think about what you want to measure, or sense. Let’s say you want to build a light sensor. You need an instrument to transform light into an electrical signal. That instrument is called a photodiode, and it does just what you want it to do: it converts light energy into electrical current. But let’s dig a bit deeper: how does the photodiode do this?

Without going into too many technicalities, photodiodes are built from specific materials and when photons hit the surface of these materials, they create something called the photoelectric effect, which disrupts the previously stable energy configuration of the material. This can generate an electric signal which is then picked up (and sometimes amplified) so it can be read by the system.

If you want to build a motion sensor, you need different types of materials, that can produce small amounts of current when they are moved or distorted. The rest of the mechanism is the same.

An example of an (almost) wearable sensor that tracks alcohol in the body. Image credits: UC San Diego.

So in essence, sensors generally work in a similar fashion: you need something (like a photodiode) that can transform your desired input into an electric current. You then pick up that electric current, amplify it if necessary, and pass it on to your computer.

A good sensor must have the ability to tell current very precisely. For instance, if the light increases slightly, so too will the current produced by the photodiode, and the sensor must be able to tell this. The better the ability, the better the sensitivity. But sensors also need to be able to withstand vibrations and temperature changes, which often affect the quality of the output.

Types of sensors

Image credits: Jorge Ramirez.

Sensors can be classified based on several different aspects. For instance, sensors can be either:

  • active (which require an external signal); or
  • passive (which work without any external signal).

Sensors can also be:

  • analog (produce an analog output, ie a continuous signal); or
  • digital (which work with discrete, digital data).

Most commonly, however, sensors are classified based on the physical property they measure. Here are some examples:

  • light sensors (which we’ve already discussed) are used everywhere, including on phones;
  • motion sensors;
  • proximity sensors, which can use different physical methods, like optical with laser, ultrasonic, or capacitive, etc;
  • temperature sensors;
  • chemical sensors, which can work for various types of chemical substances, like alcohol, smoke or gas, for instance;
  • humidity sensors (excellent for agriculture);
  • tilt sensors.

The sensor world has never been so active and diversified, which is why many now believe that sensors will usher in a new type of technological revolution.

Internet of Things and beyond

Sensors are no longer used just in engineering — in medicine and biotechnology, they are important tools that measure biological or physical processes. Environmental science as we know it today wouldn’t exist without accurate sensors, and practically every field that needs physical information uses sensors to get it. Every smart object is smart thanks to its sensors, and the more we look around us, the more objects are becoming smart.

You may have heard of the Internet of things (or IoT) — the idea of having objects around us connected in an internet-like network. This would mean that the “things” would be embedded with sensors and software, and could communicate with each other. For instance, a smarthome is a great example of how the IoT would work: your smart thermostat would turn on the heat automatically once temperature falls below a certain value, or, say, 30 minutes before you leave work, so your home is nice and cozy when you arrive. Lighting would have sensors to detect and automatically turn off when not used, and smoke/gas detectors would constantly work in the background.

Of course, the smart home isn’t the only idea of the IoT. Driverless cars would also need to be connected to the IoT so that they don’t collide with each other and keep the drivers safe. Virtually everything that benefits from automation, from medicine to high-end technology, could benefit from an IoT approach. But for all of this futuristic stuff to work, you need accurate, robust, and connected sensors.

Our world is full of sensors, and it’s unlikely to change anytime soon — if anything, we can expect sensors to play an even more important role in our lives.

Smallest-yet image sensor for medical use wins Guinness World Record

A new, diminutive optical sensor has won a place in the Guinness Book of World Records for being so, so small (and still functional).

The newly-developed camera.
Image credits OmniVision.

OmniVision, a California-based developer of advanced digital imaging solutions has announced the development of its OV6948 image sensor — a piece of gear that now holds the record for the smallest image sensor in the world.

Eagle-eyed, but small

The sensor will be used in a camera module, which the company has christened CameraCubeChip. OmniVision’s announcement (published on their website) of the new device all but earmarks it for medical use, stating that it’s meant to “address the market demand for decreased invasiveness and deeper anatomical access”. In the future, the company hopes to also expand the range of potential users to include veterinarians, dental practitioners, and the health industry at large.

And it’s easy to see why. The new sensor measures just 0.575 x 0.575 mm (1 mm = 0.03 in), while the wafer-shaped CameraCubeChip is only slightly larger: 0.65 x 0.65 x 1.158 mm, roughly the size of a grain of sand. Because of its very small size, the sensor and camera module can be fixed to disposable endoscopes and used to imagine the smallest parts of the body, from nerves and parts of the eye to the spine, heart, the inside of joints, or the urological system. Patients are bound to appreciate how small the devices are, considering that alternatives available today are uncomfortable, and can become quite painful.

The camera will also be much cooler (in terms of temperature) than traditional probes, which means it can be used for longer inside a patient’s body without posing any risk. This is due to its very modest power usage: just 25 mW (milliwatts) of power.

The new sensor has a 120-degree field of vision, a focus range of 3 to 30 mm, allows for 200 x 200 resolution, and can process video at 30 fps (frames per second). It will also be able to transmit data in analog form over a maximum distance of 4 meters.

Another important advantage of the new sensor is that it can be affixed to disposable endoscopes. Patient cross-contamination caused by endoscope reuse is a growing public health concern, one which the camera can help fix, or at least reduce.

Scientists invent phone app that accurately monitors blood pressure

Researchers developed new hardware and a smartphone app that can measure blood pressure (BP) as accurately as existing cuff devices.

Via Pixabay/rawpixel

The team of scientists from Michigan State University (MSU) also found a new, more convenient, measurement point. Stanard measurement devices use the brachial artery as the conventional measurement point, but the team discovered that measuring BP on fingertip arteries was very easy and exact.

“We targeted a different artery, the transverse palmer arch artery at the fingertip, to give us better control of the measurement,” said Anand Chandrasekhar, PhD student at MSU. “We were excited when we validated this location. Being able to use your fingertip makes our approach much easier and more accessible,” said Chandrasekhar, lead author of the study published in the journal Science Translational Medicine.

How does the app work?

The app uses two sensors: one is optical, and one is force. The optical sensor lies on top of the force sensor in a compact unit housed in a one centimeter-thick case attached to the back of the phone. Users turn on the app and press their fingertip against the sensor unit. With their finger on the unit, they keep the phone at heart level and watch the screen to ensure they are applying the correct amount of finger pressure.

“A key point was to see if users could properly apply the finger pressure over time, which lasts as long as an arm-cuff measurement,” said Ramakrishna Mukkamala, professor at MSU. “We were pleased to see that 90% of the people trying it were able to do it easily after just one or two practice tries.”

According to the WHO, raised blood pressure is estimated to cause 7.5 million deaths per year worldwide, about 12.8% of the total of all deaths. High blood pressure is a major risk factor for coronary heart disease and strokes. In addition, complications of raised blood pressure include heart failure, peripheral vascular disease, renal impairment, retinal hemorrhage and visual impairment. Treating systolic blood pressure and diastolic blood pressure until they are less than 140/90 mmHg is associated with a reduction in cardiovascular complications.

The treatment usually requires both lifestyle changes and medication, and only 20 percent of people with hypertension have their condition under control. This new phone app gives patients an advantageous alternative — keeping a log of day by day estimations would deliver an exact BP average, with periodical estimation becoming obsolete, believes Mukkamala. In this way, medication dosage will be better adjusted to each individual.

I think this is great news for all of us. I remember thinking that the incorporated sensor that measures pulse and oxygen saturation found on the back of some smartphones might need new medical updates, including blood pressure measurement. Luckily, this day has come, and the future just became brighter.

Electrick brain.

Spray-on touchscreen can turn almost anything into a sensor with a flick of the wrist

Carnegie Mellon University researchers have managed to fit the ever-so-convenient touchpad in a spray can. Using this technology, any surface, regardless of size or shape, can be turned into a working touchpad.

Electrick brain.

The researchers can turn a range of surfaces — even this brain-shaped Jell-O mold — into touchpads.
Image credits CMU.

We’re used to seeing touch sensitivity employed on flat, often small surfaces, such as tablets or smartphones. This mostly comes down to the cost associated with building the devices, and the need to install them on mechanically-resilient frames. But imagine you could take any finished object and then cheaply coat it in a touch-sensitive layer as easily as spraying some paint on it.

You can with this can

That’s what researchers at CMU have been working on. Dubbed Electrick, their spray can turn everything from walls to Jell-O into touch-sensitive sensors. The coating functions much like other touchscreens, through the shunting technology — when you touch the screen, the layers connect and a small charge is shunted to the electrodes. Several electrodes on the edge of the sensor/coating pick up these signals. By first applying electrically conductive paint-like layers onto objects and then connecting a series of electrodes to them, the researchers showed that they can pinpoint the exact point of touch on the surface using a technique called electric field tomography.

Electrick could solve some of the current limitations of touch-sensitive technology. For instance, large touch surfaces are expensive to produce, and flexible ones are still confined to research and development labs as of now. But the spray-on touch sensor can be applied “on almost anything” says Chris Harrison, assistant professor in the Human-Computer Interaction Institute (HCII), head of the Future Interfaces Group, and first author of the paper, taking on the shape as well as the flexibility of the base objects. The technology should be both accessible to hobbyists and compatible with common manufacturing methods, such as spray coating, vacuum forming, casting/molding, or 3D printing, the team reports.

The technology does have some limitations. In comparison to traditional touch devices, Electrick isn’t as accurate. But with a one-centimeter margin or error, it’s more than precise enough to comfortably allow the use of buttons, sliders, or other controls.

The team used the coating to cover objects including a 4-by-8 ft (1.2 x 2.4 meters) sheet of drywall, a steering wheel, a guitar, a Jello-O mold of the human brain, even some Play-Doh. They also used the coating to make an interactive smartphone case, which could, for example, open the camera app when held a certain way, and a game controller which could change the location of its buttons and sliders based on the game or user preference.


Overall, the team reports that the coating proved to be durable during their testing, but will not look into adding a protective coating atop the conductive layers to make the screens more wear-proof.

The findings will be presented at CHI 2017, the Conference on Human Factors in Computing Systems, in Denver later this week.

Bionic Skin.

3D-printed bionic skin can give bots a sense of touch, protect soldiers from explosions

University of Minnesota engineers have developed an innovative 3D printing process which can lay down stretchable electronics. The devices could be used to coat robots in a sensitive layer or to provide feeling-from-a-distance for surgeons.

Bionic Skin.

Image credits Shuang-Zhuang Guo, Michael McAlpine / University of Minnesota

The fabric-like material is created using a unique multifunctional 3D printer the team designed and built in their lab. It has four different nozzles and uses specialized inks to print the device up in layers. The process starts with the printer laying down an initial layer of silicone to give the device mechanical resilience, followed by two (one top and one bottom) conductive layers which act as electrodes, a coil-shaped pressure sensor, and a final ‘sacrificial’ layer to hold everything in place while they set. This last layer won’t be part of the final device but will be washed off in the final steps of the process.


The device can ‘feel’ and relay pressure, functioning very much like out skin’s tactile sensors. And this outsourcing of tactile sense could lend itself well to many applications — for example, installing this bionic skin on surgical robots would enable surgeons to actually feel around during these procedures, instead of relying solely on cameras like they do now. It could also be used to give robots a sense of touch, helping them walk or better interact with the environment.

But one of the most exciting aspects of this printing process is that the layers are fully flexible and the whole printing process can be performed at room temperature. Each of the layers can also stretch up to three times their original size. Taken together, this means that unlike conventional 3D printing systems — which use hot, molten materials — the team’s device can print directly on live human skin. The layers are also flexible and resilient enough not to hinder motion or break during use. Here’s the printer in action on a dummy.

Michael McAlpine, a University of Minnesota mechanical engineering associate professor and lead researcher on the study says the technology could eventually lead to wearable electronics to perform a wide range of tasks, from monitoring a user’s health all the way to protecting soldiers from explosives of chemicals in combat.

“While we haven’t printed on human skin yet, we were able to print on the curved surface of a model hand using our technique,” McAlpine said. “We also interfaced a printed device with the skin and were surprised that the device was so sensitive that it could detect your pulse in real time.”

“This is a completely new way to approach 3D printing of electronics,” he adds. “We have a multifunctional printer that can print several layers to make these flexible sensory devices. This could take us into so many directions from health monitoring to energy harvesting to chemical sensing.”

Another advantage of the bionic skin is that every step of manufacturing is built into the current process, so there’s no need to scale anything up for industrial production. The skin is ” ready to go now,” according to McAlpine.

Next, the team plans to expand the process to include semiconductor inks and work on printing on a real body.

The full paper “3D Printed Stretchable Tactile Sensors” has been published in the journal Advanced Materials.

Finger sensor

Dust-sized sensors might one day monitor brain nerves. No batteries required

Finger sensor

The dust-sized sensor is so small it’s on scale with fingerprints. Credit: Ryan Neely

The first dust-sized sensors were recently demonstrated by a team from UC Berkeley, United States. These can be implanted in the human body to relay back vital signs or even trigger actions. Scientists claim the battery-free neural dust motes can monitor internal nerves, muscles or organs — all in real time.

As far as internal body sensors are concerned, one of the prerequisites is to make them as small as possible. For some applications, like neural sensors, these sensors have to be even smaller than the diameter of a blood vessel. There’s only so much you can get away with miniaturization, though.

A sensor typically needs a battery to power it or some sort of power supply, an antenna to transmit and receive information, circuitry, not to mention the actual sensing electronic instruments. When faced with this sort of challenges, it really boils down to solving the weakest link in the chain — namely cut down on the most voluminous component of your sensor. In most cases, this is the power supply.

The UC Berkeley managed to scrap batteries altogether by using a piezoelectric crystal that converts ultrasound vibrations from outside the body into electricity to power a tiny, onboard transistor. The same physical phenomenon is being exploited in California to generate electricity from cars driving over highways.

Ultrasound pulses both power and read out measurements. . The backscatter signal carries information about the voltage across the sensor’s two electrodes. Credit: UC Berkeley

Ultrasound pulses both power and read out measurements. . The backscatter signal carries information about the voltage across the sensor’s two electrodes. Credit: UC Berkeley

The transistor is in contact with biological tissue, say a nerve or muscle, and when the ultrasounds cause it to spike a voltage, the biological fiber alters the piezoelectric crystal’s vibration. This vibration changes the ultrasound echo which is picked up by a receiver, typically the same device that generates the initial ultrasound pulse in the first place. So, the ultrasounds both power and read out the measurements — very clever! Ultrasounds are also more efficient than radio waves, the UC Berkeley researchers claim.

This is how scientists were able to monitor the muscles and peripheral nerves of rats: with these tiny motes measuring only one cubic millimeter. The passive sensors were powered up every 100 microseconds with six 540-nanosecond ultrasound pulses.

For this particular experiment, the team covered the motes with surgical-grade epoxy, but the next version will be coated with biological compatible films. They also want to make the sensors — currently the size of a grain of sand — even smaller. The goal is to make them no larger than 50 microns on a side or half the width of a human hair. At this scale, the specks could be small enough to nestle up to nerve axons and record their activity.

The sensor, 3 millimeters long and 1×1 millimeters in cross section, attached to a nerve fiber in a rat. Credit: University of California, Berkeley

The sensor, 3 millimeters long and 1×1 millimeters in cross section, attached to a nerve fiber in a rat. Credit: University of California, Berkeley

One of the most promising application is in brain-computer interfaces, such as the ones currently being experimented to help paraplegics control prostheses with their thoughts, just like the biological counterparts. Although great progress can be made with non-invasive devices like electroencephalogram caps, the best results are achieved with electrodes that have to be implanted straight in the brain. This, of course, involves drilling the skull. Moreover, these electrodes wear out after only one to two years.

Such electronic motes could also be highly useful as electroceutical devices — special gear used in therapy for epilepsy or to stimulate the immune system or tamp down inflammation.

“The original goal of the neural dust project was to imagine the next generation of brain-machine interfaces, and to make it a viable clinical technology,” said neuroscience graduate student Ryan Neely. “If a paraplegic wants to control a computer or a robotic arm, you would just implant this electrode in the brain and it would last essentially a lifetime.”

“The beauty is that now, the sensors are small enough to have a good application in the peripheral nervous system, for bladder control or appetite suppression, for example,“ Carmena said. “The technology is not really there yet to get to the 50-micron target size, which we would need for the brain and central nervous system. Once it’s clinically proven, however, neural dust will just replace wire electrodes. This time, once you close up the brain, you’re done.“

The findings appeared in the Neuron Journal.



Everyone might one day wear this electronic temporary tattoo that monitors your vital signs


For the past couple of years,  John Rogers, a materials science professor at the University of Illinois, has been working on his pet-project: the Biostamp. True to its name, the device is basically a tiny electronic stamp, no larger than a quarter, that sticks to the skin and can be worn seamlessly. The whole time, the Biostamp collects on a variety of vital signs, depending on the embedded sensor, and is powered wirelessly via your mobile phone. It can analyze chemicals in your sweat; blood pressure; UV radiation and much more. Basically, it’s transforming the way patients are monitored. In fact, it’s changing the way people, sick or not, monitor their health. Imagine wearing a Biostamp all the time and receiving a notification on your mobile phone to visit your doctor ASAP because your blood pressure has been too high in the last couple of days.

Medical checkups can be a real hassle, for both patients and doctors. First, a doctor checks your blood pressure, your temperature and so on. If the doctor sees a sort of anomaly, he’ll register you for further checks – this time on bulky equipment. Maybe an electrocardiogram for your heart or a blood test for diabetes.

The biostamp stretch like skin, includes flexible circuits, and can be powered wirelessly. The butterfly-shaped sensor monitors exposure to UV rays; the one at the center uses sensitive dyes to detect key chemicals in sweat; on the right, this sensor uses an electronic circuitry to measure blood pressure differences. Image: MC10

The biostamp stretch like skin, includes flexible circuits, and can be powered wirelessly. The butterfly-shaped sensor monitors exposure to UV rays; the one at the center uses sensitive dyes to detect key chemicals in sweat; on the right, this sensor uses an electronic circuitry to measure blood pressure differences. Image: James Provost

Not even a decade from now, the Biostamp might become ubiquitous that simple checkups will be handled by your smartphone. You’ll only visit your doctor when you really have to. Additionally, the wealth of data the sensors pick up will help the doctor give better diagnoses, since he’ll see when exactly your health deteriorates, for how long and so on.

Rogers and colleagues first started work on the Biostamp in 2008. Since then, he’s founded a company called MC10 to market commercial health sensors. MC10 today has about 60 full-time employees, US $60 million in venture capital and corporate investment. So far, the company only has one product for sale: the Checklight – a skullcap that precisely measures the acceleration during athlete’s head impacts. For the Biostamp, corporate interest is a lot more intense. For instance, one client currently testing it and an early investor in the company is L’Oréal, the hair and skincare giant. The two companies are now working together to develop a Biostamp sensor that monitors how heat travels across the skin under the patch. Embedded inside the patch is a tiny heat generator, and a temperature sensor. The patch could track changes in hydration as people use its products over time and more general changes as the skin ages.  “I would love to see a beauty patch on someone’s body give them skin-care recommendations,” Guive Balooch, global vice president in charge of new technologies for L’Oréal, who learned about Rogers and his work after reading of his papers.

Assortment of biostamps. Image: Randi Klett

Assortment of Biostamps. Image: Randi Klett

Other groups are researchers the possibility of using Biostamps to measure mental stress in air traffic controllers. When you’re stressed, the hands are a lot hotter. When this happens to the air traffic controller, small doses of a stress reliever drug is injected.

Here’s how the Biostamp is built:

The biostamp includes  arrays of transistors, diodes, capacitors, inductors, LC oscillators, temperature sensors, strain gauges, an LED, an inductive coil, and a simple antenna. Image: Randi Klett

The biostamp includes arrays of transistors, diodes, capacitors, inductors, LC oscillators, temperature sensors, strain gauges, an LED, an inductive coil, and a simple antenna. Image: Randi Klett

“A Biostamp is built out of stretchable circuits supported by an extremely thin sheet of rubber. To make these circuits, Rogers and his colleagues in Illinois start by fabricating their transistors, diodes, capacitors, and other electronic devices on wafers of any common semiconductor material. They typically use silicon but could also use gallium arsenide or gallium nitride. These are not ordinary semiconductor wafers; they’re kind of like the Oreo cookie of semiconductor wafers. They have a thin top layer of semiconductor material, a thicker bottom layer of the same material that acts as a rigid support during manufacture, and a sacrificial layer of a different material in between. In the case of a silicon wafer, this sacrificial layer is silicon dioxide. After the device manufacture is complete, a chemical bath eats away that central layer and frees the thin top layer.

Then a stamp made of soft silicone presses onto the wafer. Raised areas on the stamp lift away selected electronic devices in the same way a rubber stamp picks up ink from a stamp pad. After picking up the devices, the silicone stamp deposits them onto a temporary substrate, usually a plastic-coated glass plate. This plate then goes through a standard photolithography process that connects the devices with copper conductors in the form of serpentine coils, which make the connections stretchable.

The next step is to transfer the interconnected devices from the plastic-coated glass onto what will go to the consumer—a thin sheet of rubber already attached to a plastic backing sheet, with a layer of adhesive in between. To do this, a machine pushes the rubber against the array of devices and coils that are still clinging to the plastic-coated glass. A final chemical bath dissolves the plastic between the electronic circuits and the glass, leaving the circuits attached to the rubber. And the last step happens when the Biostamp gets into the hands of the user—who exposes the adhesive and sticks the rubber-backed electronics onto the skin,” writes Tekla Perry for Spectrum IEEE.

For the moment, there are some clinical trials involving the Biostamp in the United States and Europe. Commercial versions will become available late this year.

Developing smart cities: In the Spanish city of Santander, the walls will have ears

Urban noise can be quite a nuisance, but it can also provide a lot of valuable information about the city’s needs. A first of its kind project in the city of Santander will check if this data can actually be used to improve the lives of citizens and develop a better, smarter city.

Image via Ear-It

“The EAR-IT project is an EU FP7 co-funded project working over a two-years period (Oct’2012-Sep’2014) on the exiting challenges of using acoustic sensing in smart cities and smart building. With innovation and research in this area, the project will experiment in the city of Santander (Spain) and for intelligent building in Geneva, applications improving security, energy saving, traffic management and more. The project idea will conduct a large-scale ‘real-life’ experimentation of intelligent acoustics for supporting high social value applications fostering innovation and sustainability”, the project’s website reads.

Basically, they want to record sounds and see how this data can benefit residents. For example, an ambulance battling heavy traffic is a problem which could be solved thanks to this system. Pedro Malo, EAR-IT project coordinator, explains how this situation can be improved:

“As we can see, this ambulance needs to get to the hospital fast – lives can be at stake. So we’re proposing a technological solution – acoustic devices like this one – that can fast-track ambulances to the hospital by, for example, changing the traffic lights.”

The characteristic sound waves emitted by the ambulance can be picked up by sensors which will then pass it on, and traffic lights can be adapted to make way for the ambulance.

“Sensors have plenty of advantages,” says Györgi Nagy, a researcher in acoustic technologies at the Fraunhofer Institute for Digital Media Technology. “They are cost-efficient and can be used for multiple purposes. And acoustic sensors don’t need the line of sight: even if we don’t see the ambulance, we can still recognise it by the sound it makes.”

Santander is well on its way to becoming a smarter city, thanks to acoustic and electromagnetic sensors. Image via Unican.es

But there are even more advantages one could think of when it comes to this system – in the case of a robbery or gunshots, the sensors could pass on the data for a fast intervention. Juan Ramón Santana Martinez, a researcher in wireless sensor networks at the University of Cantabria said:

“We can monitor the traffic situation by measuring the noise levels on the streets, or we can even detect emergency situations: if there’s a cry for help or a gunshot, authorities can be alerted automatically.”

But it’s not just about acoustic sensors – electromagnetic sensors work too. You could for example design an app which shows you if there’s a parking spot available, and if yes, then where it is. This could help save time, gas and clear up traffic. It’s this kind of development which will lead the way for the future’s smart cities.

“By ‘smart city’ we mean a system that gathers data on various aspects of city life. It can help to manage traffic, energy consumption, or different parameters related to the environment. These systems make the city more convenient and more sustainable,” says Luis Muñoz, a researcher in wireless networks at the University of Cantabria.

But isn’t this a violation of privacy? If acoustic sensors capture all the environmental sounds, then they will also capture conversations. Won’t this pave the way for abusive recordings? Well, according to scientists, there are plenty of ears in the walls today and yet no personal conversations are recorded. What they want to implement is in no way different to recording systems which are already common in front of banks, public buildings and many other public areas.

Annika Sällström, an expert in user engagement at Luleå University of Technology’s Centre for Distance-Spanning Technology believes people won’t feel they are being spied on:

“People don’t want to be listened to, but still they can accept that audio is captured if it comes down to security and safety. We have found in our study that they can even give up a bit of their privacy for security, so if they can feel a safer city they can give up their privacy a bit.”

What do you think about this? The potential advantages of this technology are obvious – but are they worth giving up a bit of your privacy? Is there a way to grow the new generation of smart cities without giving up any of our civil liberties? I hope the answer is ‘yes’.


New wireless network will revolutionize soil testing

A researchers from the University of Southampton has developed a a wireless network of sensors that is set to revolutionize soil-based salinity measuring.

Testing the salinity levels in soils is a big deal – any salty water infiltrations can have massive effects on agriculture and sometimes, even on soil stability. At the moment, you can analyze soil salinity either indirectly, through geophysical techniques (most notably resistivity measurements, as salty water is extremely conductive), or directly – by taking soil samples and analyzing them in the lab. The problem is that resistivity only maps any salty infiltrations, without giving some clear values, while sampling takes a lot of time and money.

Dr Nick Harris, from Electronics and Electrical Engineering, worked with a group of professors from the University of Western Australia (UWA) to produce the revolutionary sensor that can carry out non-invasive measurements handily.

The sensor basically measures the chloride (salt) in the soil moisture; by linking several sensors together, he can create a wireless network that can collate and relay the measurement readings. The network can also control the time intervals at which measurements are taken in order to develop a time map.

Dr Harris says:

“Traditionally, soil-based measurements involve taking samples and transporting them to the laboratory for analysis. This is very labour and cost intensive and therefore it usually means spot checks only with samples being taken every two to three months. It also doesn’t differentiate between chloride in crystallised form and chloride in dissolved form. This can be an important difference as plants only ‘see’ chloride in the soil moisture. The removal of a soil sample from its natural environment also means that the same sample can only be measured once, so the traditional (destructive) method is not suited to measuring changes at a point over a period of time.”

The network also employs a small unit which is “planted” in the ground and just left there, and the limiting factor for the entire array is the lifetime of the sensor – which is estimated to be well in excess of 1 year. The battery-powered unit sends the data via either short range radio, Bluetooth, satellite or mobile phone network, and it also allows it to be stored on a memory card and be collected at a later time.

“These soil-based chloride sensors can benefit a wide range of applications. Large parts of the world have problems with salt causing agricultural land to be unusable, but the new sensors allow the level of salt to be measured in real time, rather than once every few months as was previously the case.”

The good thing is that you can also plant these sensors at different depths and have an accurate 3D image of what is happening with the underground salty water. He believes that the sensors can be used at a local levels by farmers, but also at a much larger scale – when planning irrigations or development strategies, for example.

“At plant level, probes can be positioned at continuous levels of depth to determine the salt concentration to which roots are exposed and whether this concentration changes with the depth of the soil or in different weather conditions. We can also measure how well a plant performs at a particular concentration and change the salt content for a few days and observe the effects. On a bigger scale, sensors could be placed at different locations at catchment scale to observe any changes in the level of salinity within a field over time, having a direct impact on irrigation strategies. We have already been able to make some interesting observations on real world chloride concentration changes over just 24 hour periods, illustrating the dangers of relying on single point, single time measurements.”

A cheap e-ink-printed multitouch sensor you can cut into any shape with only scissors

A joint team from Saarland University in Germany and the MIT Media Lab has developed a printable multitouch sensor film that you can cut to any desired shape.


Proposing cutting as a novel paradigm for ad-hoc customization of printed electronic components is truly ground breaking. The electronic ink-wires are printed through using conductive ink on flexible, thin film. Researchers have developed 2 configurations – star and tree.


They were also able to combine both layouts in a space-saving way, so that the sensor supports all basic forms – be it a heart, a tree, a cat, or whatever your heart desires.

This very direct manipulation allows the user to make virtually any surface touch-interactive, with a huge range of possible applications (interaction with home appliances, interactive walls used for discussions and brainstorming and novel ultra-thin computer interfaces); oh, and I forgot the best part: it’s incredibly cheap!

“The factory costs are so low that printing our A4-size [8.27 x 11.69 or 210 x 297 mm] film on our special printer in the lab costs us about one U.S. dollar,” says Max-Planck Institute for Informatics researcher Jürgen Steimle.

He estimates that the technology will become publicly available sometime in 2017.

Prototype tactile recording and display system for real-time reproduction of touch (credit: UCSD)

Next level user-interface tech: recording and rendering human touch

Prototype tactile recording and display system for real-time reproduction of touch (credit: UCSD)

Prototype tactile recording and display system for real-time reproduction of touch (credit: UCSD)

Since touch screen interfaces have been introduced on mass scale the way people interact with technology has been arguably revolutionized. Still, there is much more to be explored in how the sense of touch can be manipulated to enrich user interaction with tech. Recording and relaying back information pertaining to the sense of sound (audio files) or sight (photo, video files) has been successfully incorporated in technology for more than a century now. The other senses, however, seem to have been bypassed by the digital revolution, in part because they’re so much more difficult to reproduce. This might change in the future, ultimately leading to user interfaces that offer a complete, real-life experience that stimulates all human senses.

A recent research by scientists at University of California, San Diego explores the sense of touch in user interfaces. The researchers devised a set-up comprised of sensors and sensor arrays capable of electronic recording and playback of human touch. The researchers envision  far-reaching implications for health and medicine, education, social networking, e-commerce, robotics, gaming, and military applications, among others.

In their recently demonstrated prototype, an 8 × 8 active-matrix pressure sensor array made of transparent zinc-oxide (ZnO) thin-film transistors (TFTs) records the contact touch and pressure produced by the finger tips of an user. The eletrical signal is then sent to a PC, which processes the data and from there to a tactile feedback display, which used an 8 × 8 array of diaphragm actuators made of an acrylic-based dielectric elastomer with the structure of an interpenetrating polymer network (IPN). The polymer actuators playback the initial touch recorded by the ZnO TFTs, as they can dynamically shape the force and level of displacement by adjusting both the voltage and charging time.

“One of the critical challenges in developing touch systems is that the sensation is not one thing. It can involve the feeling of physical contact, force or pressure, hot and cold, texture and deformation, moisture or dryness, and pain or itching. It makes it very difficult to fully record and reproduce the sense of touch,” the researchers write in the paper documenting their work, published in the journal Nature Scientific Reports

In addition to simply playing back touch, the touch data can be stored in memory and replayed at a later time or sent to other users. “It is also possible to change the feeling of touch, or even produce synthesized touch by varying temporal or spatial resolutions,” said Deli Wang, a professor of Electrical and Computer Engineering (ECE) in UC San Diego’s Jacobs School of Engineering and senior author . “It could create experiences that do not exist in nature.”

The technology is still in its incipient form, so it’s better to view the scientists’ work as a proof of concept instead of a complete solution. The technology needs to be drastically improved to reproduce all the intricate parameters that influence the sense of touch, yet this work signals that we’re on our way there. What about smell and taste? Well, that should be really interesting to see. [READ: Music for the nose: the olfactory organ]

  • Siarhei Vishniakou et al., Tactile Feedback Display with Spatial and Temporal Resolutions, Scientific Reports, 2013, DOI: 10.1038/srep02521 (open access)