# High-stability solid-state cooled Cryo-TEM transfer holder

> **NIH NIH R43** · HUMMINGBIRD PRECISION MACHINE COMPANY · 2020 · $150,000

## Abstract

Project Summary
Project Title: High-stability solid-state cooled Cryo-TEM transfer holder
Company Name: Hummingbird Precision Machine Co., dba Hummingbird Scientific
Principal Investigator: Daan Hein Alsem
Summary:
Cryo-TEM or electron cryotomography (ECT) produces high-resolution 3D views of biological
samples in hydrated and functional state. This microscopy technique has a leading role in
structural characterization efforts of biological samples, including: intact cells, organelles,
macromolecular complexes, and proteins, facilitating basic knowledge and drug discovery. Over
the last decade, the resolution of cryo-TEM has seen an unprecedented improvement down to
below 3 Angstrom because of the advent of direct-electron detection cameras, which are orders
of magnitude more sensitive than previous TEM camera technology and new high-throughput
loading mechanisms in the latest generation of dedicated, but expensive, Cryo-TEM microscopes.
However, the resolution achieved with these new dedicated TEMs is not better than the resolution
capability of standard TEMs installed twenty years ago. There are still hundreds of these previous
models of TEMs used for imaging of biological specimens. These labs can (and in many cases
have) purchase the latest generation sensitive cameras for these microscopes, which makes that
these older microscopes are at that point not limited by their electron-optics, or their camera, but
by the cryo-TEM sample holder. The cryo- TEM holder technology used today relies on
evaporation of LN2 in a geometrically asymmetric Dewar attached to the sample to cool the
sample, which causes image instability and vibration, specifically when changing the tilt angle
when acquiring tomograms. Because of shifting mass in the LN2 Dewar and the LN2 encountering
less cooled surfaces when tilting resulting in excess boiling, the image stability in these TEM
holders is far from perfect. This project will provide scientists with a TEM cryo-transfer sample
holder that eliminates these image instability and vibration limits and allows the previously
installed cryo-TEMs to achieve the performance similar to or matching the latest generation of
dedicated and very expensive cryo-TEMs.
We are proposing to achieve this by using a cryo-TEM sample transfer holder that has a
rotationally symmetric solid-state cooling block to cool the sample. Because of the symmetry there
are no changes in forces on the holder when tilting and the solid-state cooling method assures
there is no excess boiling when LN2 is moving around during tilting of the specimen. This
eliminates sample instability and vibration that arise during tilting of the holder during acquisition
of cryo-TEM tomograms. As an added benefit, this innovation also provides a much longer cold
life of the sample (>12 hours) than current generation Cryo-TEM holders. We will achieve this by
using an ultra-cooled solid-state cold mass that has no boiling or liquid mass but is instead cold-
charged to temp...

## Key facts

- **NIH application ID:** 9908270
- **Project number:** 1R43GM135954-01
- **Recipient organization:** HUMMINGBIRD PRECISION MACHINE COMPANY
- **Principal Investigator:** Daan Hein Alsem
- **Activity code:** R43 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $150,000
- **Award type:** 1
- **Project period:** 2020-05-05 → 2021-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9908270

## Citation

> US National Institutes of Health, RePORTER application 9908270, High-stability solid-state cooled Cryo-TEM transfer holder (1R43GM135954-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9908270. Licensed CC0.

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