From Extended Nanofluidics to an Autonomous Solar‐Light‐Driven Micro Fuel‐Cell Device

Abstract

Autonomous micro/nano mechanical, chemical, and biomedical sensors require persistent power sources scaled to their size. Realization of autonomous micro‐power sources is a challenging task, as it requires combination of wireless energy supply, conversion, storage, and delivery to the sensor. Herein, we realized a solar‐light‐driven power source that consists of a micro fuel cell (μFC) and a photocatalytic micro fuel generator (μFG) integrated on a single microfluidic chip. The μFG produces hydrogen by photocatalytic water splitting under solar light. The hydrogen fuel is then consumed by the μFC to generate electricity. Importantly, the by‐product water returns back to the photocatalytic μFG via recirculation loop without losses. Both devices rely on novel phenomena in extended‐nano‐fluidic channels that ensure ultra‐fast proton transport. As a proof of concept, we demonstrate that μFG/μFC source achieves remarkable energy density of ca. 17.2 mWh cm−2 at room temperature.

Potential of AgBiI4 rudorffites for indoor photovoltaic energy harvesters in autonomous environmental nanosensors

“…During the last decade, the ETA concept demonstrated its remarkable advantages mainly in the area of photocatalysis. [32][33][34][35][36][37][38] For example, the photoanodes based on vertically aligned 2.5 μm WO 3 nanorods covered with only 25 nm thin BiVO 4 layer demonstrated ultimate water splitting photocurrents corresponding to ∼90% of the theoretically possible value for BiVO 4 , despite the very short carrier diffusion length of ∼70 nm in BiVO 4 . 32,33,37) Similar utilization of the ETA structures in PV devices can significantly broad the choice of photovoltaic absorbers by alleviating the issue of short lifetime of photogenerated carriers.…”

“…The low power output of the PV device of around 1.76 μW cm −2 is nevertheless sufficient for a wide range of electronic components and sensor devices. Considering that modern low-power wireless transmitters consume as few as 1 μJ per bit for data transmission, 38) a combination of the rudorffite PV cell and an energy storage device based on supercapacitor can be used to achieve reliable intermittent data transmission.…”

Ionic Processes in Water Electrolysis: The Role of Ion-Selective Membranes

“…83 Another approach may be to use chemically and thermally robust inorganic materials with relatively large nanochannels that were recently shown to exhibit Grotthuss conduction. 86,87 Future designs could include hybrid approaches using organic− inorganic materials that afford a vast parameter space of organic synthesis, allowing tunability in functionality and chemical robustness in combination with the high thermal stability of inorganic frameworks.…”

Effect of finite spatial and temporal resolutions on super-resolution particle tracking velocimetry for pressure-driven flow in a nanochannel

“…The elds of nano uidics exploiting 10 to 100 nm spaces with ultrasmall volumes (aL to fL) and dominant surface effects has rapidly developed to realize applications such as high-e ciency transport of molecules and ions (Ishibashi et al 2012;Pu et al 2004), high-speed proton conductor (Pihosh et al 2017), and single cell/single molecule analyses (Cipriany et al 2012;Shirai et al 2018;Nakao et al 2019). Simultaneously, researches utilizing arti cial nanochannels have revealed various unique phenomena of liquid behavior and mass transport in con ned spaces with increased surface-to-volume ratio such as higher viscosity (Tas et al 2004;Li et al 2012; Kazoe et al 2020), lower dielectric constant (Morikawa et al 2015) and enhanced proton transfer (Liu et al 2005;Tsukahara et al 2007; Chinen et al 2012).…”