Upcycling of Agro-waste: Biobased Piezoresistive Sensor by Exploiting the Natural Porous Structure of Cornstalk Pith for Detecting Pressure Signals

The utilization of natural biomass materials for the transformation into biobased green flexible sensors with specific electronic properties has garnered the attention of a wide range of researchers. Of these, considered as an agricultural waste, natural corn stover (NCS) has received less attention from researchers, despite its abundance, extremely low cost, and porous internal structure. This paper proposes a capillary phenomenon absorption method (CAM) to easily and low-costly modify inside corn stover pith (CSP) with aqueous natural rubber (NR) and CNT/PEDOT:PSS activation solutions (AS), which converts CSP into the biobased piezoresistive material NR40/AS@CSP. This material has a stable resistance change signal under continuously varying or constant external pressure. In addition, it has a large sensing range (5.5–500 kPa), fast response time (less than 400 ms), and strong antifatigue performance (the signal amplitude is basically the same for 300 s of fast continuous loading). With the exceptional characteristics of NR40/AS@CSP, it can be processed into CSP-based pressure sensors (CSPSs). This biobased transducer has proven their utility in practical application experiments such as pressure warning devices, Morse code, and large area sensing arrays. The CSPS obtained by modifying discarded maize stover exhibits great potential as a replacement for conventional polymer piezoresistive sensors.