# Tunable Ampere phase plate for low dose imaging of biomolecular complexes

## TL;DR

This paper introduces a tunable, support-free phase plate for transmission electron microscopy that uses magnetic fields generated by current-carrying wires to enhance contrast in imaging biological specimens.

## Contribution

It presents a novel magnetic phase plate device that is tunable and support-free, validated through experiments, theory, and simulations for improved biological imaging.

## Key findings

- Successful experimental validation of the phase shift
- Enhanced contrast in biological specimen imaging
- Theoretical and simulation support for device effectiveness

## Abstract

A novel device that can be used as a tunable support-free phase plate for transmission electron microscopy of weakly scattering specimens is described. The device relies on the generation of a controlled phase shift by the magnetic field of a segment of current-carrying wire that is oriented parallel or antiparallel to the electron beam. The validity of the concept is established using both experimental electron holographic measurements and a theoretical model based on Ampere's law. Computer simulations are used to illustrate the resulting contrast enhancement for studies of biological cells and macromolecules.

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Source: https://tomesphere.com/paper/1702.02029