ENVIRONMENTAL MONITORING

The environmental challenges facing our planet have never been greater, with the impact of climate change, pollution and habitat loss becoming increasingly apparent around the world. By enabling us to gather more environmental data, including data from previously inaccessible locations, IoT technology can help us to better understand the world around us and inform effective action.

Every year billions of data points are taken around the planet, whether by small sensor devices, meteorological stations or satellite systems. If you can make any part of it cheaper, more connected, more autonomous or easier to configure and maintain, you save thousands of hours of researcher time.

Often used in harsh or remote locations, environmental IoT systems need to be robust enough to withstand extreme conditions and easy to deploy and maintain – ideally removing the need to wade through a river or climb a mountain to change batteries or reset devices. Our researchers are developing and deploying IoT systems tailored to these specific demands.

Understanding glacier dynamics

To anticipate and manage the effects of climate change, it’s crucial to understand the effect of global warming on glaciers and the resulting sea level rise. However, the behaviour of glaciers is not well understood because it’s so difficult to model what’s happening beneath hundreds of metres of ice.

13 https://glacsweb.org/

For almost two decades our researchers have been generating new knowledge about glacier dynamics13, most recently at project sites in Iceland where they were the first to put custombuilt, internet-connected sensors underneath glaciers to measure temperature, stress, weather and subglacial movement in real time.

This involved designing a whole system tailored to glacier conditions, from new sensing technologies and communications protocols through to fabricating unique, super-robust sensor capsules. Developments included building in autonomy to enable the sensors to gauge the available power and communication channels and adapt their activity levels accordingly. A range of wireless communications technologies, including low-power radio links and mobile phone networks, were deployed to transmit data from the sensors to a base station on the ice, then to the internet via a nearby reference station.

Reflecting the multidisciplinary nature of IoT research, the team included expertise across computer science, electronics and glaciology.

Measuring ice flow

More recently the research team has been measuring glacial ice flow using the latest generation of low-cost real-time kinematic (RTK) dGPS units. Powered by solar energy, the system automatically provides location measurements from synchronised dGPS units, which wait for a static RTK fix and then sleep between sessions.

The readings are sent once a day to a web server via the Iridium satellite network, allowing the system to operate anywhere in the world. The fixes are accurate, quick to acquire and generate small amounts of data for transmission, reducing the power requirements by around a 50th compared to traditional systems and opening up the possibility of year-round live monitoring.

Testing IoT interoperability in the Scottish Highlands

Another project took researchers to the Cairngorms in Scotland to set up remote monitoring of hydrological, peatland and frozen ground processes14 The underlying aim was to test the standardisation and interoperability of the different elements of IoT environmental monitoring systems.

Typically, networked environmental sensing systems are difficult to set up because of incompatibility between the different components. The aim of this project was to see whether using standards and Internet Protocols would support an interoperable, internetconnected IoT system. The results showed the effectiveness of this approach, with benefits in terms of scalability, integration, management and robustness. The proof-of-concept project has laid the foundations for new IoT sensing research, as well as showing its potential for use in the Earth sciences.

Sensing salt levels in soil

Another area where IoT systems have huge potential is soil condition monitoring. Our researchers have developed sensors to detect the levels of chloride (salt) in soil, working in partnership with the University of Western Australia. In Australia, deforestation and increased demands on water supplies have altered the water table, allowing salt to rise upwards through the ground. In the long term, soil salination poses a threat to food security globally, as too much salt renders agricultural land unusable.

The sensors draw on a longstanding research interest at Southampton in the field of active inks that can detect or respond to things in their environment. Unlike traditional circuit board manufacturing, which uses a subtractive process that strips off copper to leave behind the desired circuitry, these inks can be screen printed directly onto a surface. It’s a flexible and relatively simple process; any material that is printable can be used, and it can be printed in any shape and layered with other materials to suit the required function.

14 https://mountainsensing.org/

A substrate of ceramic is printed with silver as the conducting material, which is isolated with a layer of glass, followed by a printed layer of the active sensing material. In the case of chloride detection, the active material is silver chloride – which reacts with chloride in the environment – mixed with glass and liquid to form an ink.

Using this process the researchers fabricated sensing elements which can be inserted to the soil. The system uses two electrodes which effectively make half a battery; the environmental chloride provides the electrolyte, so if there is chloride present a voltage is created. Measuring the voltage between the two electrodes indicates how much chloride is in the soil.

The researchers are planning to extend this work to the sensing of phosphates used in fertiliser, which increase crop yields but harm the environment when they seep into the surrounding watercourses.

Powering environmental sensors

Another strand of research is looking at a new way of powering IoT devices for environmental monitoring. Environmental sensors are generally solar powered, but over time dust or plant growth can block out the light, reducing the amount of energy they can generate. Our researchers are working on an alternative that uses temperature changes at sunrise and sunset to generate energy.

This innovative technology turns the temperature change into a pressure change; as the air in a sealed cylinder warms up it expands, which increases the pressure. The pressure is used to move a piston and drive a generator. By changing the type of gas inside the cylinder the device can be tuned to work over a particular temperature range. Because the energy is generated only at dawn and dusk, it is harvested and stored for use when the sensor is active.

it will generate enough energy to run lowpower sensors and communication systems.”