Your mobile phone already knows where it is, how you're holding it, what you're saying to it and how fast you're moving.
Yet with significant improvements in mobile sensor technology just around the corner, this is only the beginning chapter in the era of self-aware devices and continuous data logging. There's much more to come.
We're now used to phones and tablets recognising when they're being held upside down and flipping the screen accordingly, but even this kind of technology is a relatively new innovation that has only become commonplace in the last three or four years.
One of the earliest consumer products to showcase these sensors wasn't a phone at all, but the Nintendo Wii games console.
Making sense of sensorsThe sensors we've grown accustomed to, and which you can find in almost every new device on the market, include the accelerometer, for measuring movement and orientation, and the gyroscope, for measuring angular rotation across three axes and giving more accuracy to the accelerometer reading.
Location services are taken care of with a magnetometer for detecting magnetic North and some form of GPS chip or a related variant to plot your position on the map.
On top of this there's the proximity sensor for recognising when you move your phone up to your face during a call and an ambient light sensor for boosting brightness levels in dark environments.
Like every electrical component, these sensors continue to get smaller, more powerful and cheaper. The total cost of all the sensors inside your brand new mobile phone is probably less than a handful of pounds, though as with any other hardware there are budget and premium options available.
The list price of the accelerometer in the new iPhone, for example, is $1. Whatever the cost, they've become an integral part of the mobile experience: imagine a tablet that doesn't change orientation when you rotate it, or a phone that can't give you directions back home.
The cutting edgeAs 2013 draws to a close, there are yet more sensors marking their ground. Apple's iPhone 5S and iPad Air come with an M7 tracking chip, which adds to the motion sensing capabilities of these devices. In practice, it can tell the difference between walking and driving, and take certain actions (such as switching off Wi-Fi) if you haven't moved for a while.
If you're on a train, the M7 chip can be used to tell the phone to stop trying to attach to public networks as they whizz by. Fitness apps, meanwhile, can access accurate data about your movements with no need for a wristband.
Samsung isn't shy of throwing everything it can into a handset, and this is certainly the case when it comes to the sensors packed into both the Galaxy S4 and Galaxy S5 handsets.
These phones includes both temperature and humidity sensors, the data for which you can access through the S Health app, enabling the phone to keep an eye on the state of the environment around you.
There's also a barometer for measuring atmospheric pressure and a gesture sensor that detects hand movements through infrared rays.
So much for the here and now: what about the months and years to come? In short, more sensors and greater accuracy.
We spoke to Emiliano Miluzzo, Senior Member of Technical Staff at US mobile giant AT&T, to get an insight into what could come next. As part of his role at AT&T Labs Research, he specialises in mobile sensing systems and big data analysis. "The trend of adding more sensors to mobile devices will continue," says Miluzzo.
"It would be great to have air and water quality sensors, some forms of medical sensing, 3D/stereo cameras, even radar and sonar... the wishlist could certainly grow if we could have an understanding of how quickly sensor miniaturisation will proceed."
Sensory overloadHow would you like a phone that could track your heart rate and emotional state, perhaps putting on some soothing music as soon as you start to get anxious?
According to Freescale Semiconductor director Kaivan Karimi, this is possible using sensors that cost just a few pounds.
"Your device will get to read your emotions," Karimi told the GigaOM Mobilize Conference in October. "That means you can track people's emotions remotely... your device will know you significantly better than you do."
The microelectromechanical systems (MEMS) built into our phones are made of silicon, but scientists are now experimenting with MEMS running on an organic polymer more suitable for implanting in the human body.
Once the cost and time taken to manufacture these components comes down, we could be able to monitor health and activity from inside our own bodies. They could even be used to control bionic limbs.
UV light sensors are also in the stages of early testing by manufacturers including ROHM. Find out how much sun cream you need, or how clean your hands really are, or how much you've had to drink, all courtesy of your phone.
Imagine the difference it would make to a check up at the doctor's if you had two months' worth of data on file rather than relying on your own memory and a quick five minute conversation.
On a broader level, disease and health patterns can be tracked more accurately across countries and continents.
Researchers at the University of California, Berkeley have built a working prototype of a pollution sensor small enough to fit inside a mobile phone, giving governments and health officials the opportunity to measure smog and dangerous chemicals across cities (as well as giving you a warning when it's time to don a face mask). Mobile air monitoring sensors are also being developed by the US Environmental Protection Agency.
Meanwhile, Antonio D'Alessandro and Giuseppe D'Anna, seismologists at the National Institute of Geophysics and Volcanology in Italy, have run tests on the iPhone 4 and 5 to demonstrate how mobile phones could be used to detect earthquakes.
The sensors within our handsets need to improve, but eventually they could act as early warning systems and get aid to those in need more quickly.
Next-generation sensors will make a difference on a local and a global scale. AT&T's Emiliano Miluzzo again: "By turning a smartphone into the equivalent of a Swiss Army knife, we could change lives in both high-tech and developing countries because what people need would be in the palm of their hands anytime and anywhere.
"Not only will users get immediate answers to their problems, but governments too will be able to run their infrastructures more efficiently."
"Medical data could be continuously streamed back to the cloud," continues Miluzzo. "If something was flagged as anomalous, it would trigger an alert for medical intervention.
"Governments could rely on crowdsourced 24/7 pollution level measurements, people in developing countries could rapidly check the quality of their water, EEG headsets could let people control their devices simply through their thoughts, and radar and sonar sensing could let people be more aware of their surroundings."
The smarter homeAs sensors become smarter, so will all of the other gadgets and equipment in our homes. The sensor-packed smartphone of the future won't work in isolation, but as part of a larger network of devices, whether it's the thermostat at home or the Wi-Fi enabled lamppost out on the street, each with their own integrated miniature monitoring components.
STMicroelectronics is one of the companies leading the charge in sensor development. It's working on technology that combines readings from an accelerometer, magnetometer, pressure sensor and Wi-Fi scanner to accurately pinpoint your location indoors.
That means whether you're trying to find a bookshop in a shopping centre or a restaurant in a hotel, the tech can make life much easier when you can't get a GPS lock.
Samsung, meanwhile, is currently showing off a Home Innovation Space at Harrod's, featuring smart, Internet-enabled washing machines, fridges and other electrical goods.
Once your phone has the ability to work out which floor you're on, you might never have to press a light switch again, whether you're at home or at a hotel. What's more, your Internet-enabled fridge could suggest a meal based on the nutritional value of the food you've already eaten, as tracked by your phone.
Then there's your weekly trip to the gym — the MyoLink muscle sensors from Somaxis can detect how well your workout is going, while the Cardiio app is able to measure your heart rate through your iPhone's camera.
This tech is already in the early stages of development as of today, and it shouldn't take long before gym equipment can automatically adapt to your fitness levels without any input from you.
Let's not forget gaming either — the Samsung Galaxy S4 can already tell when you're looking away from the screen, and once mobile cameras are smart enough to detect your mood, then the gameplay could adapt accordingly to make life easier or slow you down.
As 3D and stereo cameras become the norm, so gesture and facial recognition will improve.
Brave new worldsA final look ahead from Emiliano Miluzzo: "What's exciting is that smartphones and tablets will turn into our personal assistants, ready to sense our surroundings and take actions on our behalf.
"To achieve this, new and advanced sensing capabilities will be always needed — a process that hardware miniaturisation will only accelerate. And it's fascinating to see how researchers and developers exercise their creativity to come up with unthinkable apps and ideas with the sensors available today.
"We measure this by the very large community participation in what it is known as smartphone sensing research."
Phone sensors offer portability backed up with computing power and the ability to report back from the remotest of locations. Whether it's monitoring your blood sugar levels or warning about an impending avalanche, nothing is beyond the realms of possibility when it comes to future innovations.
Smartphones have already revolutionised many aspects of our lives, and they're only just getting started.