How can wearable electrodes become more sustainable, Laura Kallo?
In an exclusive article for OPE journal, Laura Kallo from Screentec explains how the Finnish company is tackling the environmental impact of disposable medical electrodes.
The article was first published in OPE journal 47. You can find the epaper under the following link: OPE journal
Global trends in health and wellness are driving demand for innovative measurement solutions. With an ageing population and rising healthcare costs, more sustainable health monitoring solutions are urgently needed. Through collaboration and the EU project Sustronics, Screentec from Oulu, Finland, aims to reduce environmental impact and promote industry-wide adoption of more sustainable practices by developing wearable electrodes with eco-friendly substrates and conductive pastes such as copper and carbon.
The increasing use of disposable medical electrodes poses a pressing environmental challenge. Traditional materials are no longer viable due to their finite nature and the environmental damage caused by excessive e-waste. In response to this growing concern, Screentec is exploring innovative approaches to reduce the environmental impact of the electronics industry. Through collaborations with industry partners, research institutes and active participation in the EU project Sustronics, Screentec is driving the development of wearable electrodes with more sustainable substrates and conductive pastes such as copper and carbon.
Screentec’s commitment to sustainability is reflected in its exploration of various materials and technologies. Additionally, Screentec integrates surface mount technology (SMT) components onto diverse substrates such as plastic, paper or textile. These efforts aim to reduce the environmental impact while maintaining the effectiveness of the wearable electrodes.
Exploring three electrode solutions specifically designed for ECG, EEG and bioimpedance measurements, Screentec focuses on: disposable electrodes with plastic and silver printing; electrodes with sustainable substrates and copper and carbon printing; and multi-use electrodes integrated into textiles with plastic and silver printing. While each solution has its advantages and challenges, the integration of sustainability into wearable electrodes promises significant environmental benefits and industry-wide adoption of eco-friendly practices.
Solution 1: Disposable electrodes with plastics and silver prints
The first solution involves disposable electrodes made from conventional plastic substrates and silver conductive prints. Screentec is currently a manufacturer of these electrodes, ensuring convenience and reliability in various medical applications. Single-use electrodes should be designed to be as simple as possible. Key variables in their design include wear time, wear location and the need for stretchability. In addition, they should have an easy to use and cost-effective connector solution.
Printed disposable electrodes have several advantages over standard single-use ECG electrodes. Each use ensures high signal quality, which is critical for accurate diagnosis. They can be worn for days or weeks, depending on the application. They also offer high performance and reliability with a typically long shelf life due to the stability of the materials used. The cost of these electrodes is moderate to high driven by the cost of silver, but the cost per day per use is generally lower.
However, there are disadvantages. They have a significant environmental impact due to disposal of non-biodegradable materials. Over time, this results in a higher price per use, taking into account environmental costs and the need for continuous replacement. Improvements in sustainability can be achieved by using paper, recycled plastics or compostable substrates and by substituting copper or carbon for silver paste.
Solution 2: Electrodes with sustainable substrates and copper and carbon prints
The second solution features disposable electrodes made from environmentally friendly substrates combined with copper and carbon prints. This option improves sustainability by using renewable or recyclable substrates and less precious conductive materials. Its functionality is comparable to traditional electrodes offering effective conductivity.
Silver pastes are widely available from several suppliers and their processing is an established practice that has been used for decades. Carbon pastes are also widely available and are typically processed in a similar way to silver pastes. “However, conductive traces made with carbon have a resistance value approximately 1000 times higher than those made with silver. This makes carbon unsuitable for applications that require low resistance, such as EEG,” says Mikko Paakkolanvaara, CTO of Screentec. Copper pastes, which have been available for printed electronics for a few years now, present a promising alternative. “Although there are currently fewer suppliers of copper pastes compared to silver or carbon, copper offers similar resistance values to silver, making it a suitable option for low-resistance applications such as EEG electrodes.” However, copper’s tendency to oxidise poses additional challenges. “The processing of copper pastes typically requires an extra step during manufacturing, usually during the curing or sintering process, to prevent the formation of a non-conductive layer due to oxidation,” adds Paakkolanvaara.
The shelf life of these sustainable electrodes depends on the stability of the substrate, which can be shorter than that of plastic-based electrodes. However, the cost is generally lower than that of silver-based electrodes, with savings coming from the use of more abundant materials such as copper and carbon.
Solution 3: Multi-use electrodes integrated into textiles using plastics and silver prints
The third solution is to integrate multi-use electrodes into textiles using plastics and silver conductive components. However, reusable electrodes should be designed to be as durable as possible to increase sustainability. TENS electrodes are a good example of a cost-effective multi-use solution. Integrating electrodes into textiles presents additional challenges in terms of product structure. Regular rinsing with water or machine washing is often required, and factors such as washing time, temperature and spin cycles have a significant impact on their lifespan. Users may often clean electrodes against instructions, which can lead to complicated reclamation issues. In addition, connectors need to be designed for multiple use.
Reusable electrodes have a lower environmental impact and a longer lifetime, making them more sustainable over time, especially when considering the number of times they can be used. The sustainability of these electrodes improves significantly with increased use, as their higher initial cost is offset by their extended usability over many cycles. This results in a lower price per use, provided the number of uses is high enough to justify the initial investment. However, reusable electrodes integrated into textiles require careful consideration of washability, which adds complexity to their design. There is also the potential for signal quality degradation over their lifecycle and a higher price per product compared to single-use options. In addition, there is a risk of contamination if the electrodes are not properly cleaned and maintained, which can pose health risks.
The author
Laura Kallo works as a sales and marketing representative at Screentec, specialising in the MedTech industry. With extensive experience in marketing communication, she focuses on new customer acquisition and CRM management. Kallo is dedicated to developing and implementing B2B marketing strategies and creating engaging content that resonate with industry professionals. Working with cross-functional teams and stakeholders, she is responsible for ensuring a smooth and consistent customer experience.
About Screentec
Founded in 1989 with circa 60 employees and headquartered in Oulu, Finland, Screentec is a contract development and manufacturing company specialising in printed electronics.
Screentec develops and manufactures medical electrodes, diagnostic devices and durable user interfaces. The company also serves a wide range of industries, including medical, automotive and consumer electronics, providing customised solutions to meet specific customer needs. It also offers a full range of consultancy and product development services. Screentec’s promise to its customers is “to enable our customers’ visions to become reality by supporting them from product development through to production”.
Caption: Laura Kallo from Screentec; PET substrates combined with carbon paste to develop lightweight, durable and flexible electronic components. Included: a test sample of paper-based substrates with silver prints. (Image source: Screentec)