Bio-based substrate for flexible electronics - application to a 2.45 GHz wearable patch antenna

In this paper, a bio-based and biocompatible polymer, Cellulose Laurate (CL), is proposed for flexible radio-frequency (RF) electronics. The synthesis of CL films together with their characterizations (chemical, thermal, mechanical and dielectric) are presented. The results obtained allow considering this material for RF flexible applications as a possible alternative to petrosourced substrates. Therefore, CL has been used to fabricate a flexible patch antenna that operates in an industrial, scientific and medical (ISM) frequency band. The central frequency selected is 2.45 GHz. The antenna fabrication process is based on the combination of laser structuring and the use of copper adhesive tape. Measurements of the antenna reflection coefficient and radiation patterns show that CL is a good candidate as a RF substrate. Furthermore, it is demonstrated that the antenna performance is only slightly impacted under bending conditions.