What are ultrasound probes?

An ultrasound machine is not just a piece of hardware; it’s the ‘brain’ behind the scenes, armed with the computing power to process, measure, and display the images it captures. Whether it’s powered by a battery or plugged into the mains, this machine is at the heart of the ultrasound experience.

But here’s where the true enchantment lies – the probe, (also referred to as a transducer). Plugged into the machine, this nifty device is your gateway to the world of ultrasound waves and the images they create. It’s like the conductor of a symphony, orchestrating the transmission and reception of ultrasound waves, which are then transformed into visual images by your trusty machine.

In this article, we will focus on the two most popular probe types: Convex and Microconvex.

So, how does the probe work its magic?

At its core are crystals with ‘piezoelectric’ properties, residing in the head of the probe. When an electronic current flows through them, these crystals vibrate, generating ultrasonic waves. These waves are then skillfully focused in the desired direction by the probe’s ‘lens.’ It’s a ballet of precision and technology.

When the ultrasound waves strike their intended target and are reflected back, the crystals vibrate once more. This time, their energy is converted into an electric current, which travels back along the wire to the ‘machine.’ There, it’s processed and displayed as a coherent image – the masterpiece of the ultrasound world.

How do I choose the right probe? Convex versus Microconvex.

Just as there are different tools for specific jobs, there isn’t just one type of probe. Each one is meticulously designed to excel in a particular task. Some, like the Microconvex probe, are perfect for imaging tiny to medium-sized species (from hedgehogs through to pygmy goats), offering astonishing clarity of images and ease of use. However, for giant canine breeds like Great Danes, larger goats and pigs, a Convex probe would be more appropriate, so it’s important to think about what species/size breed you’ll be scanning most. The choice of probe is crucial to achieving the best results in your ultrasound examinations.

In addition to the physical dimensions of the probes, their suitability for specific tasks hinges largely on the frequency at which they emit ultrasound waves. “Frequency”, in this context, is the rate at which the probe releases ultrasound waves per second.

The frequency holds a pivotal role as it directly impacts both what we can visualize and the clarity of the resulting image. Lower frequencies are adept at penetrating deep into the subject, albeit at the expense of image quality. Conversely, higher frequencies may not delve as deeply, but greater depth isn’t appropriate for smaller animals and they compensate with superior image quality.

For instance, take the Convex probe as an example – it typically operates within the range of 2.5 to 5 MHz, indicating that it emits 2.5 to 5 million waves per second, depending on your settings. While this frequency might seem relatively low, its larger head makes it well-suited for scanning larger animals. On the other hand, the Microconvex probe operates at a higher frequency, ranging from 3.5 to 7 MHz, and features a smaller head, rendering it ideal for a wide range of smaller to medium-sized animal examinations.

Here’s a final summary of these two probe types:


The footprint of the probe is relatively large, or the area that makes contact with the skin. A convex probe is more of use for giant breed dogs, large animals such as sheep, goats, pigs, and cows. A convex probe has a lower frequency of between 2.5-5MHz. This for larger animal’s results in better penetration, but unfortunately the tradeoff is a lower resolution.


If only scanning small animals this maybe the only probe you’ll ever need!
The head of a Microconvex probe is smaller than its larger relative of the convex probe. It operates at a higher frequency, which means its penetration is reduced, this means that it is less suited for large animals. Although it cannot penetrate so far it does have its own advantages, it has a higher frequency at 3.5-7MHz which means it offers higher resolution images. As a smaller probe it offers more maneuverability.


To recap, probes (or transducers) are the unsung heroes of ultrasound, transforming ultrasound waves into meaningful images. They come in various shapes, sizes, and frequency ranges, tailored to specific tasks, subjects, and image quality requirements.

What’s next on our ultrasound journey? We’ve covered quite a bit in this article, but there’s more to explore. Stay tuned for future posts delving into the specifics of Linear, Linear Rectal and Mechanical probes. In the meantime, we’re here to help answer your questions, whether you’re considering a purchase or simply seeking knowledge. Our team of professional sonographers, with over 25 years of combined experience, is here to assist you, free of charge. Your queries and challenges are our opportunities to shine – count on us for guidance whenever you need it.