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Full title of the project: Continuous monitoring of hypothermia in elderly people by the novel integrated wearable sensor system based on cellulose hydrogel and metallic nanowires (Marie Curie Actions – European Commission)

More about the project:

One common influence of ageing is that it makes an individual susceptible to hypothermia, which is known to be causing low body temperature (35°C). Hypothermia could be detected at early stages by monitoring various physiological parameters such as ECG signal, skin temperature and body movement. Owing to their flexibility and stretchability, wearable sensors could provide long-term continuous recordings of electrophysiological activity for monitoring hypothermia in elderly people.

Wearable temperature, pressure and strain sensors were studied in various forms by many research groups. Those approaches utilized complex and high-cost photolithography techniques, which make the devices very difficult to commercialize. Besides, poor processability and lack of skin compatibility of stretchable polymers, used as substrates, prevent the practical use of these materials. However, solution-processable nanomaterials offer a unique way to reduce the cost and complexity, while cellulose hydrogel is an easy-processable and skin friendly polymer.

Thus, in this project, we aim to develop an integrated wearable temperature and pressure/strain sensor based on solution-processable nanowires and cellulose hydrogel to monitor hypothermia in elderly people via measuring pressure, strain and temperature. The pressure/strain sensor will be prepared via laminating two silver nanowire printed cellulose hydrogels sandwiching a pressure-sensitive dielectric layer. The temperature sensor will be fabricated via transfer printing of gold nanowires on the cellulose hydrogel substrate. Next, the pressure/strain and temperature sensors will be laminated to form the integrated sensor. Finally, the sensors will be used to treat real patients.
 

Research Concept and Methodology

The project work will include the following research stages:

1. Cellulose hydrogel preparation
2. Synthesis of ultralong nanowires
3. Production of porous dielectric layer
4. Fabrication & characterization of pressure/strain sensor
5. Fabrication & characterization of temperature sensor
6. Fabrication & characterization of integrated sensor
7. Field Study

Originality and Innovative Aspects

Wearable sensors for healthcare monitoring are an innovation-based emerging technology, and they have created huge market opportunities. The WEARSENSNANO action has been designed to solve existing problems via several original and innovative approaches:

• Integrating the pressure and strain sensor in a single platform in such an application;
• Measurement of capacitance in the pressure/strain sensors and resistance in the temperature system (will prevent the interference of signals in the integrated sensor system);
• Utilization of cellulose hydrogel as the substrate in the temperature and pressure/strain sensor system (as it is skin friendly, easy to process, low-cost and flexible);
• Fabrication of porous dielectric layer with tunable porosity by Ni foam template and thus tunable sensitivity (creating air-void microstructures in the dielectric layer increases the sensitivity of the pressure/strain sensors);
• Using ultra-long nanowires (>100 μm) as conductors in the sensor systems (as shorter nanowires (<100 μm) lose their conductivity and sensitivity upon stretching);
• Ligand exchange of nanowires with shorter molecules before the annealing process (since the conventional annealing temperature of nanowires (250-300°C) is detrimental to polymer substrates);
• Use of gold nanowires (AuNWs) in the temperature sensor owing to their high conductivity, high linearity at 25-50°C and easy processing (to our best knowledge, it will be the first time to use AuNWs as conductor in the temperature sensor);
• Microcontact printing is a low-cost, high-throughput and simple technique to generate patterns on any kind of substrate and a very convenient method for solution-processable nanomaterials. 

Continuous monitoring of hypothermia in elderly people via measurement of ECG signals, body temperature and muscle activities is very important. To our best knowledge, there is no academic work and/or commercial product focused on this problem. WEARSENSNANO will be an original and innovative approach to deliver a wearable integrated sensor system, applicable for continuous monitoring of hypothermia in patients.

Interdisciplinary aspects

WEARSENSNANO brings together various disciplines – materials science, chemistry, physics, processing, medicine – to overcome problems of the state-of-the-art integrated wearable pressure/strain and temperature sensors for health monitoring.

Materials science and technology are at the core of this project. Nanomaterial synthesis and printing require knowledge and skills in chemistry and physical chemistry. In addition, fabrication and electrical characterization of sensors relates to electronics and sensors, while hypothermia monitoring serves human health care. Moreover, WEARSENSNANO data output will be in need of ‘Internet of Things’, ‘Big Data’ and ‘Artificial Intelligence’.

Contact information: 

Accountable project leader: Prof. Jaana Vapaavuori (jaana.vapaavuori@aalto.fi)

MSCA IF Researcher: Dr. Fevzihan Basarir (fevzihan.basarir@aalto.fi)

Project page on the Research Aalto portal:

The project is being implemented in collaboration with other existing projects of the Multifunctional Materials Design research group - ModelCom and SUPER-WEAR.