Carbon allotrope-based textile biosensors: a patent landscape analysis

Smart textiles are a wide category of products that embed ultra-technical fibers to implement sensing or actuating functions: electrodes and sensors able to measure bio-signals and detect several parameters - such as body temperature and motion, heart rate, electrocardiogram (ECG), electrical brain activity, electrical muscle activity, breathing rate, SpO₂, and blood pressure - and actuators to produce thermal or mechanical actions.

These smart components are integrated into textile fiber, clothes, and elastic bands and support various applications in several fields, including healthcare, security, military, and fashion.

One very recent technology is the fabrication of fibers or layers based on carbon allotrope materials such as graphene, reduced graphene oxide (rGO), carbon nanotubes (CNTs), and carbon black (CB).

This report aims to provide a patent landscape analysis on carbon allotrope-based textile electrodes and biosensors to measure biosignals and detect several parameters such as body temperature and motion, heart rate, electrocardiogram (ECG), electrical brain activity, electrical muscle activity, breathing rate, SpO₂, and blood pressure explore the newest technological advancement and the exploitation areas. Espacenet, a free-of-charge patent database provided by the EPO (European Patent Office) and containing data on more than 140 million patent publications from over 100 countries, was used as the reference database. The patent search was carried out by combining precise keywords and classification symbols. Both classification schemes (IPC – International Patent Classification and CPC – Cooperative Patent Classification) were used. As a result of this study, a total of 227 patent documents were found between 2004 and 2023. The first patent application claiming a fabric electrode arrangement with carbon black as conductive material was filed in 2004 by Philips. 2021 was the year with the highest patent filings, with 36 documents. The United States was ranked first with 126 patent documents. Carbon nanotubes and graphene are the most patented carbon allotrope materials, while body temperature, motion, and heart rate measurements are the main disclosed applications.

We also analyzed the Orbit database obtaining 288 items (vs 227) with only 238 still active records (148 granted and 90 pending): the first application by Philips on an electrode arrangement is confirmed (but filed in 2002), and the patents distribution shows a peak in the period 2016-2020 (146 records available), while today it seems to be stable or even decreasing (“only” 52 record in the half period January 2021-June 2023).

This outcome suggests that this material and related technology has reached its maximum exploitation or has not demonstrated a disruptive output.