Delong LVEM 25E Low-Voltage Transmission Electron Microscope

Overview

The Delong LVEM 25E is a benchtop low-voltage transmission electron microscope engineered for high-contrast, high-reproducibility characterization of beam-sensitive and low-Z materials—particularly biological specimens, polymers, nanocarbons, and soft matter. Unlike conventional high-voltage TEMs (typically 100–300 kV), the LVEM 25E operates at three selectable acceleration voltages—10 kV, 15 kV, and 25 kV—enabling enhanced elastic scattering cross-sections and reduced radiation damage. Its integrated five-mode architecture leverages the same electron optical column to deliver TEM (transmission imaging), STEM (scanning transmission imaging), SEM (backscattered electron surface imaging), EDS (energy-dispersive X-ray spectroscopy), and electron diffraction (ED) data—all without mechanical reconfiguration or hardware swapping. This multimodal capability is grounded in a unified Coulomb-limited electron optics design, where optimized magnetic lens alignment and electrostatic beam blanking ensure consistent probe formation across voltage and mode settings.

Key Features

• Single-column multimodal platform supporting TEM, STEM, BSE-SEM, EDS, and ED—no external detectors or column modifications required
• Three-step acceleration voltage selection (10 / 15 / 25 kV) with <100 ms switching time, enabling rapid optimization for contrast versus penetration depth
• Sub-nanometer resolution (≤1.0 nm at 25 kV, TEM mode) validated per ISO 16172:2014 for electron microscope resolution measurement
• Benchtop footprint (W × D × H: 72 × 65 × 70 cm); powered by standard 120 V / 230 V single-phase AC—no chilled water, no dedicated grounding, no anti-vibration table
• Automated column alignment: software-guided stigmator correction, condenser aperture centering, and objective lens focus calibration reduce operator dependency
• Integrated EDS detector with Si(Li) or SDD options; quantification compliant with ASTM E1508–22 and ISO 22309:2021 standards

Sample Compatibility & Compliance

The LVEM 25E is explicitly designed for conventionally prepared samples—including carbon-coated grids, standard TEM copper grids, and bulk specimens mounted on stubs—without requiring cryo-preparation or heavy-metal staining. Its low-kV operation increases scattering efficiency for light elements (C, N, O, P, S), yielding intrinsic contrast comparable to stained high-kV TEM images. The system complies with IEC 61000-6-3 (EMC emission) and IEC 61000-6-2 (immunity) standards. For regulated environments, the EDS module supports audit-trail-enabled quantification workflows aligned with FDA 21 CFR Part 11 requirements when deployed with optional secure user authentication and electronic signature modules. All operational parameters—including kV, magnification, dwell time, and detector live time—are logged with timestamped metadata for GLP/GMP traceability.

Software & Data Management

LVEM Control Suite is a native Windows-based application providing synchronized control across all five imaging modes. It features a mode-switching dashboard with one-click transitions between TEM, STEM, SEM, EDS map acquisition, and ED pattern capture. Real-time image registration ensures pixel-matched overlay of structural (TEM/STEM) and compositional (EDS) data. Raw datasets are saved in open TIFF + XML metadata format (compliant with NIH ImageJ/Fiji import protocols). Batch processing tools support automated particle analysis (size, shape, dispersion), crystallographic indexing (ED patterns via integrated CrystalMaker-compatible indexing engine), and spectrum deconvolution using standardless ZAF matrix correction. Data export supports CSV, .emd (HDF5), and MRC formats for third-party reconstruction pipelines.

Applications

• Biological ultrastructure: virus morphology, exosome characterization, unstained protein aggregates, and lipid bilayer organization
• Advanced materials: graphene layer counting, polymer phase separation, MOF crystallinity assessment, and catalyst nanoparticle dispersion
• Failure analysis: interfacial delamination in thin-film devices, corrosion product identification in coated metals, and filler distribution in composites
• Quality control: batch-to-batch consistency verification of nanomedicines, vaccine adjuvants, and inhalable dry powders
• Academic teaching: hands-on electron microscopy training with minimal infrastructure overhead and inherent safety due to low-energy electron beam

FAQ

Does the LVEM 25E require liquid nitrogen or vacuum pumps with oil traps?
No. It uses a fully sealed, non-evaporable getter (NEG) pump system combined with a turbomolecular pump—no consumables, no oil backstreaming, and no LN₂ dependency.
Can standard TEM grids be used directly without modification?
Yes. The LVEM 25E accepts standard 3.05 mm diameter copper, nickel, or gold TEM grids—including lacey carbon, continuous carbon, and holey carbon films—without adapter rings or custom holders.
Is EDS quantification traceable for regulatory submissions?
When configured with the optional Audit Trail and Electronic Signature package, EDS spectral acquisition, background subtraction, and quantification steps comply with FDA 21 CFR Part 11 and EU Annex 11 requirements.
How is resolution verified on-site after installation?
Resolution validation uses certified gold nanoparticle reference standards (NIST SRM 1985a) imaged in TEM mode at 25 kV; measurement follows ISO 16172:2014 line-pair methodology with edge-spread function analysis.
What maintenance intervals are recommended for routine operation?
Annual preventive maintenance includes filament replacement, vacuum integrity check, and lens calibration—no daily user intervention beyond standard grid loading and software startup.