Foldable-circuit-enabled miniaturized multifunctional sensor for smart digital dust

Smart dust, which refers to miniaturized, multifunctional sensor motes, would open up data acquisition opportunities for Internet of Things (IoT) and Environmental protection applications. However, critical obstacles remain challenging in the integration of high-density sensors, further miniaturization of device platforms, and reduction of cost. Here, we demonstrate the concept of smart digital dust to address these problems, the results of which combine the benefit of (i) maturity of complementary metal-oxide semiconductor (CMOS) processing approaches and (ii) unique form factors of emerging flexible electronics. As a prototype for smart digital dust, we present a millimeter-scale multifunctional optoelectronic sensor platform consisting of high-performance optoelectronic sensor cores and commercially available integrated-circuit components. The smart material-assisted optoelectronic sensing mechanism enables real-time, high-sensitivity hydrogen, temperature, and relative humidity (RH) sensing based on a single chip with ultralow power consumption. Such a microsystem presented here introduces a viable solution to the multifunctional sensing need of IoT and could serve as a building block for the rapidly evolving future framework of smart dust.