Fig. 1: Design of cryo-ET reconstruction for photoresist polymers in a liquid film.

a Schematic of preparing the photoresist specimen in a vitrified liquid film. Ultraviolet light transfers pre-designed pattern onto the polymer-based photoresist on a wafer. The exposed photoresist is subsequently dissolved in a liquid film of developer, which further undergoes plunge freezing to immobilize the photoresist polymers in the vitreous ice for preserving polymers’ native hydrated state. b Schematic showing cryo-ET reconstruction of photoresist polymers in the vitreous ice. A series of images captured from tilted angles ranging from –60° to +60° with 3° increments are collected to obtain multidirectional projections of the photoresist polymers, which are processed for 3D reconstructions of photoresist polymers in the vitreous ice.