Nanoribbon- and nanowire-based field-effect transistor (FET) biosensors have stimulated a lot of interest. However, most FET biosensors were achieved by using bulky Ag/AgCl electrodes or metal wire gates, which have prevented the biosensors from becoming truly wearable. Here, we demonstrate highly sensitive and conformal InO nanoribbon FET biosensors with a fully integrated on-chip gold side gate, which have been laminated onto various surfaces, such as artificial arms and watches, and have enabled glucose detection in various body fluids, such as sweat and saliva. The shadow-mask-fabricated devices show good electrical performance with gate voltage applied using a gold side gate electrode and through an aqueous electrolyte. The resulting transistors show mobilities of ∼22 cm V s in 0.1× phosphate-buffered saline, a high on-off ratio (10), and good mechanical robustness. With the electrodes functionalized with glucose oxidase, chitosan, and single-walled carbon nanotubes, the glucose sensors show a very wide detection range spanning at least 5 orders of magnitude and a detection limit down to 10 nM. Therefore, our high-performance InO nanoribbon sensing platform has great potential to work as indispensable components for wearable healthcare electronics.

Layered hafnium diselenide (HfSe2) is an emerging Van der Waals semiconductor in which a hafnium layer is sandwiched between two selenium layers. Owning to its indirect band gap with magnitudes close to silicon's band gap and high predicted carrier mobility, hafnium diselenide material is a strong candidate for device applications. Here, the effect of laser treatment on 2H‐ HfSe2 devices is shown in ambient conditions using µ‐Raman spectroscopy. It is shown that an emerging Raman peak evolves with increasing laser exposure time. It is also shown that top‐down fabricated 2H‐HfSe2 devices exhibit an anomalous p‐type behavior post laser treatment, with Ion/Ioff ratio as high as 103. This anomalous conductivity change can be observed after thermal and electrical annealing. For bottom‐up devices, it is observed that p‐type conductivity with remarkable Ion/Ioff ratio reaching 104. This conductivity switch can also be shown on 1T‐HfSe2 devices post laser irradiation and high Vds bias treatments. Based on the circuit model, this conductivity switch is attributed to contact doping caused by an increase in the Schottky barrier height at each contact, which shifts the Fermi energy closer to the valance band. These results demonstrate a unique conductivity switching mechanism for HfSe2‐FET devices.

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