Monolithically-integrable and scalable 2.4 GHz MIMO backscatter system based on large-area electronics

Future embodied artificial intelligence (EAI) and Internet of Things (IoT) systems envision trillions of wireless sensing nodes embedded in the environment. Passive backscattering enables low-cost, energy-efficient communication, but adequate range in dense deployments requires high-spatial-resolution beamforming. We push large-area electronics (LAE) into the gigahertz regime to build multiple-input multiple-output (MIMO) backscattering systems with directive beamforming, exploiting LAE’s scalable, monolithic integration over flexible, meter-scale substrates. While conventional LAE is restricted below 100 MHz, we reach 2.4 GHz using our proposed thin-film transistor (TFT) resonant switch, incorporated into a novel switch matrix architecture. We experimentally demonstrate two 2.4 GHz backscattering systems using self-aligned zinc-oxide (ZnO) TFTs: (1) a 4-input 4-output MIMO reflector with independent input and output beamsteering; (2) a backscatter transmitter combining input beamforming with quadrature phase-shift keying (QPSK) modulation. These results establish LAE as a viable platform for high-performance, cost-effective wireless surfaces, enabling massive deployment of intelligent IoT nodes.