Skin sensors for health care: paper-based flexible and wearable pressure sensor

• Autor(a) principal: Simão, Miguel Martim Chambel
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/134280
• topic: silver nanowires; microwave-assisted polyol synthesis; screen-printing; bacterial cellulose; spray coating; dip coating; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

The interest and need in portable, comfortable and durable health care sensors have increased along the years, due to their practicability and potential in helping people monitoring their vital signs. However, an all biodegradable low-cost sensor still poses a challenge to fabricate. So, cellulose is being used in the nanoscale form, due to filling all the necessary requirements with their excellent properties. The same can be said for metals like gold, silver and copper, which in the form of nanowires makes them great alternatives as sensing materials for pressure sensors. This work aims to develop a facile craft, low-cost, completely biodegradable, paper-based flexible and wearable pressure sensor for health care. The AgNWs are produced by the microwave-assisted polyol synthesis and purified with 3 decantation phases. The sensor substrate is made by pressing the bacterial nanocellulose (BNC) of nata de coco. The interdigitated electrodes (IDEs) are then screen-printed on its surface. The tissue paper is dip coated with the AgNWs, placed in the middle of the IDEs and encapsulated with the BNC, concluding the sensor construction. The sensor displayed a fast response time of 1.8 ms, a recovery time of 0.8 ms and it also showed high stability during 15000 cycles. The best sensitivity values achieved were 12.05 kPa-1 (0.031-1.4 kPa), 4.29 kPa-1 (1.4-2.8 kPa), 1.59 kPa-1 (2.8-5.6 kPa) and 0.38 kPa-1 (5.6-14 kPa), with the 6 dip coating cycles paper Tork on the sensor. The lowest detectable pressure was 31 Pa and the minimum and maximum energy consumption values recorded were 3.75×10-5 W and 1.32×10-2 W with a 2V working voltage.