A field-effect transistor (FET) based on ultrathin Ti3 C2 -MXene micropatterns is developed and utilized as a highly sensitive biosensor. The device is produced with the microcontact printing technique, making use of its unique advantages for easy fabrication. Using the MXene-FET device, label-free probing of small molecules in typical biological environments and fast detection of action potentials in primary neurons is demonstrated.

Anti-counterfeiting patterns are encrypted with nanotaggants that are selectively excited at distinct wavelengths. Decryption is realized by examining the temporal color or graphic responses of the pattern under various illumination wavelengths. The covert color and graphic codes that are designable through control of the nanotaggant composition are expected to provide high-level security.

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