Laboratory microinjectors: how can very-low-volume microinjections be performed?

At the heart of cellular manipulation, microinjectors deliver ultra-low volumes — from the picolitre to the nanolitre — with the repeatability that underpins experimental success. Paired with a micromanipulator and glass capillaries, they enable the introduction of DNA/RNA, proteins, dyes or compounds into cells, embryos, oocytes or tissues. Pressure control, pulse duration, anti-backflow counter-pressure, foot pedal and method presets: everything is designed for precision, sample safety and operator ergonomics.

What are the different types of microinjectors, and how do you choose the right one?

We distinguish three main families. The pneumatic models generate adjustable compressed-air pulses (pressure, duration, frequency) and a holding pressure (or back-pressure) that prevents medium being drawn back into the capillary. Highly versatile, they excel with live cells and embryos for volumes on the order of pL–nL with minimal shear stress.

Key selection criteria: available volume and pressure range, fine control of pulse duration (ms to s), stability of the back-pressure, compatibility with your capillaries (ID/OD), solution viscosity, ergonomics (foot pedal, display, saved profiles), integration into your set-up (micromanipulator, stereomicroscope, anti-vibration), and sterility requirements (in-line filters). Calibration is typically performed by ejecting into oil and measuring droplet diameter, or using fluorescent tracers.

For durability, favour oil-free air lines, replaceable filters and easy seal maintenance. Modern electronic systems cut sample waste thanks to rapid set-up and reproducible profiles.

In which fields is a microinjector used?

The life sciences make it a core tool: CRISPR editing of embryos from fish/Xenopus, microinjection of mRNA, proteins and morpholinos. In pharma/biotech, it is used for functional screening, vector validation and controlled delivery of compounds into primary cells. In environmental toxicology, it enables precise micro-doses on aquatic models for dose–response studies. In neuroscience, it is used to load tracers or modulators into isolated neurons. In reproduction/IVF research, it supports oocyte injection. Finally, in microfluidics, it feeds devices and droplets with ultra-low volumes during imaging and biophysics experiments.

Available microinjector types

Microinjector

Frequently asked questions about microinjectors

How do I choose between pneumatic and hydraulic?
Pneumatic systems excel at short, repeatable pulses. Hydraulic systems provide a very stable continuous flow, ideal for viscous solutions or prolonged injections.

What volume range can be delivered?
Depending on the model and capillary, expect from a few pL to several nL per pulse, with repeatability improved by back pressure and pulse duration.

What is the purpose of back pressure (hold/back-pressure)?
It prevents medium from entering the capillary, stabilises the meniscus and ensures consistent volumes from one pulse to the next.

How can I precisely calibrate the injected volume?
Common approach: eject into oil, measure droplet diameter under the microscope and calculate the volume. Fluorescent tracers help with verification.

Which capillaries should I choose?
Match ID/OD to cell/embryo size and viscosity. A clean bevel and proper polishing minimise damage and improve flow.

What are good maintenance practices?
Flush lines, replace filters, check seals and foot pedal, protect from oil. Regular servicing maintains pressure stability.

Should the compressed air be filtered?
Yes—use dry, oil-free air with a 0.2 µm filter to preserve sterility and extend the life of internal valves.

Can injection profiles be saved?
On electronic models, yes: pressure, duration, cycles. Useful to standardise CRISPR or high-throughput series of embryos.