Some devices are simple, yet, they make our lives better for various reasons. Ultrasonic transducers undoubtedly fall into this category. From the first technological experiments with ultrasound back in 1917, used for submarine detection, the idea sparked people's curiosity from all walks of life. Soon, they started employing ultrasonic devices in many different areas.
Many people tend to mix up the terms "sensor" and "transducer" and use them interchangeably. However, there is a technical distinction between the two. The latter term is a collective term for sensors and actuators, which create an electric pulse by converting the echo. Now that we cleared that up, we can explore the topic of transducers and see how they work in practice. See this website for more.
A Little Tech Background
As a sound-based sensor, the ultrasonic transducer operates by receiving an electrical signal and turning them into a sound wave. Next, the wave travels through the air and hits an object, then travel back to the transducer and is again converted to an electrical signal. This is the basic working principle of all ultrasonic sensors. The upper frequency limit for these devices is 40kHz, way above what humans can hear.
Sometimes people debate whether ultrasonic transducers are superior to infrared sensors or vice versa. IR sensors detect objects using an infrared transmitter, and you operate it by adjusting a potentiometer. IR is less effective with reflective surfaces, liquids, bulk, and dark materials, whereas ultrasound transducers excel in all these situations. You could say that IR, though useful in its own right, has more limited scope.
Sensors can be easily affected by background noise and fail to produce accurate results. The noise can come from ventilator noise, drills, electrical generators, motors, etc. Fortunately, ultrasonic sensors can suppress this interference to some degree. Still, it's always best to double-check the readings and, if possible, eliminate the background noise so you can avoid making errors.
The area right in front of the transducer which prevents it from measuring correctly is called the dead zone. But what's the obstacle if there's nothing there, you may ask? Physicists know the culprit well: it's the extended vibration of the transducer which follows the pulse, also known as ringing. The solution is to wait for the ringing to disappear so the device can receive the echo properly.
Some General Characteristics
These types of sensors are beneficial in many ways. Sensing different substances and measuring all kinds of materials makes them suitable in many industries. Well-known for their accurate readings, they are robust and can operate in adverse conditions, thanks to the simplicity of the working principle.
Transducers don't need physical contact to measure distances, so you can locate them wherever you wish. It only requires an ultrasonic echo to provide you with accurate results, depending on the properties of the detected object.
The best thing about ultrasonic transducers is that they don't discriminate. They will detect any solid or liquid object, no matter the color, shape, or transparency. Their targets include wood, plastic, metal, glass, water, sand, etc. An exception would be soft materials like wool, cashmere, or hemp: they tend to absorb the sound instead of sending it back.
There are a couple of disadvantages that need to be mentioned to get a more realistic picture. We already mentioned background noise, but atmospheric movements can also affect the measurement accuracy. Next, they have a slow reaction, especially compared to optical-based sensors that operate with the speed of light instead of sound. Also, they have low angular measurement due to the acoustical beam width.
Categories of Transducers
The following paragraph is a little more scientific, but don't let it put you off: explaining it in simpler terms will help you grasp the general purpose of each transducer, so you can recognize them more easily in the future if you need to use one. They differ in the arrangement of piezoelectric crystals.
The first type is the linear transducer, where the crystals are arranged linearly. It is excellent for clinical applications such as breast examinations, vascular checks, etc. The second type is the convex transducer, also called standard by some experts. Here, the crystal arrangement is curved, while the beam is convex, so doctors use them to examine organs deeper inside the body. Finally, we have phased array transducers with stacked crystals, primarily used for heart examinations.
Piezo Transducers in Medicine
People have long been aware of the therapeutic potential of transducers. It's because they offer a minimally invasive approach and softer treatment compared to other well-known procedures. Piezo or pressure transducers are very effective in therapy, both as means of diagnosis and part of the actual treatment.
Ultrasound can be focused or unfocused in medical procedures, and you can use it for different purposes. Usually, doctors employ ultrasonic transducers for targeted drug delivery, dissolution of blood clots, cartilage therapy, the disintegration of kidney stones, tissue ablation, and so on. Healthcare workers always look for the best minimally invasive solutions, and ultrasonic sensing is right there at the top.
It also plays a significant role in eye examinations, especially before cataract surgery. Here, sensing is used to determine the length of the eye axis, an exact procedure that demands expertise and attention. For this reason, oculists need to be familiar with ultrasonic transducers before making a move.
Human error can be devastating in the medical sphere, so it's best to use precise technology to avoid blunders that could seriously endanger the patient. A good example is the application of transducers on infusion pumps. They make monitoring easier and adjust the flow speed as accurately as possible. Also, our little sensing devices can inform the controller if there's a discrepancy between preset values and the actual liquid weight.
A Closing Point
Ultrasonic transducers continue to be exploited in many areas by providing valuable data because of their versatility, ease of use and setup, accuracy, and resilience. It's impossible to tell how they will be used in the future, but their reputation can only improve.