How do self-powered sensors work?

We are fast moving towards a world where there is going to be no distinction between what’s digital and what’s not - By this we mean that nearly every object around us is going to be connected to the internet in some way. If that sounds a bit far fetched, just look around you right now - how many things can you see that are connected to the internet? Let’s face it - even though you were probably using the net in 2010, you didn’t have smart ACS, smart TVs, smart watches and well, you get the point. 

This is where technology is at today - it’s not just about transferring information through computers and phones - it’s about using information to optimise pretty much everything that happens around us. 

This is what is meant by the term Internet of things. IoT is all the rage now. Everything seems to have something to do with IoT. The idea is very simple. In the recent past, our data collection capacity has gone through the roof - today, we are able to collect, store and process literally thousands of times more data than just two decades ago. Not to mention the fact that we do so incredibly cheaply. Add to this the fact that we have no shortage of internet access and presto, you have a winning formula!

It stands to reason that with the sort of mind-boggling data processing abilities that we have acquired in the recent past and the widespread availability of tools such as artificial intelligence and machine learning to crunch data towards practical applications, we would move on to implementing such systems to optimise all manner of processes in our world. 

And so, using that premise as a starting point, the IoT revolution started, leaving radical disruption in its wake. No industry on earth would look the same anymore. The basic IoT feedback loop of collecting data, scouring it for usable patterns and then implementing progressively more efficient iterations caught on like wildfire. There was practically nothing on earth that this basic framework couldn’t apply to. 

It is against this background, that we must understand the emergence of self-powered sensors as a crucial technological innovation in this new and exciting era of hyper-connectedness. 

Driven By Necessity

To better understand the massive impact that self-powered sensors, it’s essential to understand what necessitated them in the first place. 

What was the problem that they were designed to solve?

Let’s take the example of a modern manufacturing facility. Depending on what the factory is manufacturing, such a facility would have any number of dedicated sensors that are tasked with collecting various kinds of data such as pressure, temperature, humidity etc. 

Traditionally, most of the components involved in such manufacturing facilities were hardwired - i.e they weren’t mobile. This meant that these sensors could not be used in sealed conditions - which severely limits their usefulness in many cases. Variables like flow, pressure etc are quite crucial in many manufacturing processes. This meant that there was a pressing need for wireless sensors that could be deployed in a variety of settings across manufacturing processes. 

And so we got wireless sensors. But that was just one half of the riddle as it turned out. Wireless sensors came with a caveat - if there were to be no wires, it meant that they needed to be powered by batteries. This was an awkward and inconvenient compromise at best. While battery-based wireless sensors did solve some of the problems of hardwired sensors, they came with their own set of new problems - it was dangerous to use batteries in sealed environments; especially those that involved extreme physical conditions. Moreover, while batteries enabled sensors to be deployed in hard-to-reach locations, this also proved to be a major pain point when it came to replacing them or performing routine maintenance. 

Self-powered sensors emerged as a viable solution for both these problems. They presented a very elegant solution to the battery problem. They were able to draw the tiny amounts of power needed for their operation straight out of their surroundings!

Energy harvesting for the win

So, we come back to our central question - how do self-powered sensors work?

They make use of a technology called energy harvesting. Energy harvesting or energy scavenging essentially refers to ultra-low power integrated circuits drawing tiny amounts of ambient energy from their surroundings and using it to power their operation. 

This makes them entirely autonomous. It is hard to overstate just how much of a breakthrough energy harvesting represents for IoT setups. When wireless sensors are completely self-powered, there is no limit as to where they can be deployed - deep inside pipelines, on mountain tops, under water, well you name it. Remoteness just isn’t a factor when you don’t have to factor in battery replacements, no matter how infrequent they are. 

Typically, a self-powered sensor is designed to draw power from vibrations (piezoelectric energy harvesting), temperature gradients (thermoelectric energy harvesting) or radio waves (RF energy harvesting). 

Most designs for self-powered sensors include a transducer that harvests the ambient energy and converts it into electricity, an interface circuit that conditions the energy into a suitable form that is apt for use and a load component which either stores the energy or uses it. 

Self-powered sensors at work

Let’s try and wrap our heads around how a setup involving batteryless sensors would work. For the sake of variety, let’s go from factories to farms. After all, smart farms are changing the face of agriculture as we know it. 

Let’s assume our farm uses a relatively basic sensor suite that consists of three sets of sensors - to measure soil moisture, humidity and temperature. This setup makes use of three types of batteryless sensors to measure each of these three variables. 
Like we discussed in the previous section, it’s not very hard to see why these sensors would have to be batteryless - they are going to be placed under the soil and in various hard-to-reach vantage points across the farm which spans several hectares of land. Some of these sensors will be buried under the soil for 20 years, never to be disturbed - that simply will not be possible if they included batteries that needed to be replaced. 

These sensors located at various locations on the farm continuously collect data which they relay to a cloud-based dashboard that uses AI software to check for usable patterns and opportunities for optimisation. When actionable insights are uncovered, they are readily implemented and thus, the feedback loop continues. 

This represents a very elementary model of how self-powered sensors can be used in an IoT-system. The nature and function of these systems can be pretty much anything.

Flexible, reliable and economical

In the long run, integrated circuits that use energy harvesting make for a whole bunch of advantages. Firstly, they offer users a total peace of mind in that there are very few restrictions as to where they can be deployed. All a user needs to do is find a batteryless sensor that suits their needs and just deploy it - it just stays there for years upon years just doing what it’s supposed to do. 

Moreover, self-powered sensors make for a great deal of savings over the lifetime of an operation. However, more than any of these advantages, the biggest value that self-powered sensors bring to the table has got to be that they are more ecologically sensible. Simply put, they are just light years ahead of their battery-based counterparts in terms of sustainability and ecological impact. 

It’s no surprise then that self-powered sensors are all set to take the world of IoT by storm across the board.