Sensor networks, wearable printed electronics and AAL

Wearable printed electronics will play a central role in Active Assisted Living

By Alan Hodgson, Chair IEC TC 119

Sensors provide information about objects, or people and their environment. Networks of sensors in the shape of wearable electronics and integrated into the living environment will support Active Assisted Living (AAL) into the future. Sensors and printed electronics will be increasingly integrated into smart wearable devices to facilitate the implementation of AAL.

digital temperature sensors woven into textile
Digital temperature sensors are woven into a textile to make smart temperature sensing textiles (Photo: Swiss Federal Institute of Technology Zürich, Electronics Laboratory - Wearable Computing)

Sensors key to the Internet of Things

Sensors can be considered as the data sources of the Internet of Things (IoT). In the wearables space, these devices harvest information from wearers and their environment. These sensors will be integrated into wearable smart devices (WSDs), which in turn will be connected to the IoT to facilitate AAL.

These wearable sensor networks can be organized in a number of ways and the different implementations of these are reflected in the standardization work of various IEC Technical Committees (TCs) and Subcommittees (SCs). It is useful to look at the component systems of these sensor networks to illustrate how this may be achieved.

Pervasive sensors

Currently most individual sensor elements are made using traditional semiconductor type manufacturing processes and are thus standardized as part of the work of IEC TC 47: Semiconductor devices, and of Working Group (WG) 1: Semiconductor sensors of IEC SC 47E: Discrete semiconductor devices. Amongst their active projects are documents covering wearable sensors for glucose, humidity, temperature and light. IEC SC 47E/WG1 work can give useful insight into the performance testing of such sensors.

Sensors are becoming pervasive in the modern electrotechnically-enabled society. Data published earlier this year suggests that “of the 20 000 new products that were introduced at the Consumer Electronics Show this year, probably 15 000 have some type of sensor embedded” (see Tech Trends 2016 in e-tech January/February 2016). The growing pervasiveness of sensor technology was highlighted in Sensors everywhere (e-tech March 2016).

Harnessing the power of sensors in networks

On their own, sensors can give some information, but, connected together, they can reveal much more. A WG of the Joint Technical Committee for Information Technology, set up by the International Organization for Standardization (ISO) and the IEC, ISO/IEC JTC 1/WG 7: Sensor networks, covers the reference architecture for this area. An additional dimension that is particularly pertinent to wearable electronics is wireless connected sensor networks. A comprehensive overview of these Wireless Sensor Networks (WSNs) was given in the IEC White Paper Internet of Things: Wireless Sensor Networks.

It is worth stressing that the concept and implementation of these WSNs will extend to more domains. Smart cites/homes/energy implementations will use the same concepts to connect the infrastructure to the IoT.

Wearables and IoT

Wearable devices can be considered as the human interface to the IoT. As AAL will need this human interface, IoT initiatives are an important link in the implementation. ISO/IEC JTC 1 is also active in this area and set up WG 10: Internet of Things. In common with other JTC 1 committees, WG 10 has produced definition and vocabulary documents and reference architectures for IoT systems. It is now moving on to produce a Technical Report on IoT use cases.

Printed Electronics

Using printing techniques to manufacture electronics assemblies is an attractive prospect for wide area electronics. This is because printing techniques allow industry to make devices and structures over a much wider area than do semiconductor production systems. As printing processes are open to roll-to-roll processing, they are also a route to flexible electronics, (see Printing electronics anywhere, in e-tech August 2016).

IEC TC 119: Printed Electronics, works specifically in this domain. It prepares Standards for the terminology, materials, processes and equipment that will facilitate the industrial development of printed electronics. The ability to print onto flexible substrates over a wide area is an enabling technology for WSDs and in particular for textile electronics. As a result, TC 119 is looking closely at how printed electronics can support these developments. It is currently preparing IEC TR 62899-250, a Technical Report on material technologies required in Printed Electronics for Wearable Smart Devices, due to be published in the first half of 2017. Further work is now being initiated on documents covering materials for flexible WSDs, such as stretchable substrates and inks.

Systems integration

It is recognized within printed electronics that printing techniques alone cannot provide the entire functionality for the WSDs needed to implement AAL. For the foreseeable future, these wearables are likely to consist of hybrid devices, implemented through a combination of printed and conventional silicon electronics. For this reason there are active liaisons running between IEC TC 119, and IEC TC 47 and IEC TC 110: Electronic display devices. Assembling sensors into networks and connecting these with power and the outside world represents a significant challenge. IEC TC 91: Electronics assembly technology, is therefore similarly an important part of these liaison arrangements, which also provide a bridge between the relevant industries and a meeting place for discussions.

The challenge of systems integration with a particular focus on WSDs was addressed in e-tech in January 2016.

Demand for technologies to come together in WSDs

There is a real market demand for these technologies to come together in WSDs. AAL looks to be a likely stimulus for this. To actively facilitate this, it is necessary to give additional support and attention to this area. The IEC Standardization Management Board (SMB) has responded to this need with the creation of a Strategy Group, SMB SG 10: Wearable Smart Devices, with the expectation that this group will make recommendations back to the SMB on the ways in which the IEC can best support this process. With a membership of representatives from the key IEC TCs previously mentioned, the first task for SG 10 was to come to an understanding of terminology in this area. The group identified the wealth of wearables-related activities going on within the IEC community but also highlighted some existing gaps.

These activities have culminated in a report for the SMB with recommendations on the route forward within this community and a set of priority actions.

AAL enabling technologies

Sensor networks integrated into IoT-connected wearable devices will be an enabling technology for AAL. The IEC community is already well placed to cover most of the standardization activities in this area, but some gaps remain and these have been addressed by SMB SG 10. Working as a community, the IEC is in a good position to help develop this technology for Active Assisted Living.AAL

Gallery
digital temperature sensors woven into textile Digital temperature sensors are woven into a textile to make smart temperature sensing textiles (Photo: Swiss Federal Institute of Technology Zürich, Electronics Laboratory - Wearable Computing)
Black/polymer gas sensors are fabricated on a flexible polymer substrate to create an "electronic nose" Black/polymer gas sensors are fabricated on a flexible polymer substrate to create an "electronic nose", which can detect different solvent vapors and classified them accordingly (Photo: Swiss Federal Institute of Technology Zürich, Electronics Laboratory - Wearable Computing)
 Graphene-based electrochemical device/patch with thermoresponsive microneedles for diabetes monitoring and therapy Graphene-based electrochemical device/patch with thermoresponsive microneedles for diabetes monitoring and therapy. This device both monitors blood glucose and delivers medication when needed (Photo: Hui Won Yun, Seoul National University)