Liquid metal enabled plant injectable electronics

Abstract

Extensive efforts have been made on utilizing conductive materials to monitor plant growth states. However, traditional methods are facing difficulties as physiological signals are usually concealed within plant tissues. Here, we propose a new conceptual plant injectable electronics based on the fluidic properties and high conductivity of liquid metals, which can not only resolve the existing challenges but also endow plants with diverse electronic capabilities. Following this principle, the basic electronic components (resistors, inductors, and capacitors) are successfully fabricated by injecting liquid metal into the target sites of the living plant. Furthermore, we demonstrate typical applications derived therefrom, including highly stable electrodes, long-term working sensors, and stealthy antennae with variable characteristics. Specifically, the resulting liquid metal injectable electrodes exhibit outstanding electric signal capture capability (over 2000% improvement versus printed electrodes), and remarkable anti-interference characteristics compared to conventional rigid needle electrodes. Injectable resistance and capacitance sensors provide ever-useful ways for real-time monitoring of plant position and physiological signals. More importantly, the capacitive sensor obtained by injection gives access to information about the interior of the plant that cannot be detected from non-injectable capacitive sensors otherwise. Additionally, antennas invisible from the outside with variable characteristics are manufactured and evaluated in situ in living plants, further justifying the capability of the plant injectable electronics. The present principle suggests an unconventional strategy to combine plants and electronics, which signifies a paradigm shift and is expected to serve as a basic platform for additional investigation in plant electrophysiology, electronic plants, and plant robots.