Developing next-generation digitizer chips for ultrasound imaging inside the heart
Kevin Pelzers defended his PhD thesis at the Department of Electrical Engineering on March 4.
Cardiovascular diseases are the leading cause of death worldwide, responsible for nearly 18 million deaths each year. The burden is highest in low‑ and middle‑income countries, where advanced surgical procedures are often too costly or inaccessible. Even when treatment is available, heart surgery carries significant risks and often requires lengthy recovery. To enable safer, more effective, and more affordable surgical procedures, medical ultrasound is used to image the heart. In his PhD research, Kevin Pelzers focuses on advancing high‑quality imaging from inside the heart by developing a miniature, ultra‑low‑power digitizer chip for Intracardiac Echocardiography (ICE) catheters.
When evaluating small structures inside the heart, external imaging is not sufficient. Capturing fine details requires placing the imaging device directly inside the heart. This is the purpose of Intracardiac Echocardiography (ICE), in which an imaging catheter equipped with miniature ultrasound transducers is inserted into a vein at the groin and guided toward the heart. Although similar in function to the probes used for pregnancy ultrasound, an ICE catheter is far smaller - only about 3 millimeters in diameter, with 2 meters of cable.
The requirements for ICE catheters
The electronics inside an ICE catheter must be very small and consume little power to ensure safe operation within the body. Because of these constraints, current hospital catheters contain only minimal electronics and send analog signals to an external system through many long, thin wires that are prone to interference. These wires are hand‑soldered, making them expensive and susceptible to defects. Since each catheter is used only once, the costs increase even further.
A new digitizer chip
To address these challenges, Kevin Pelzers developed a tiny, low-power digitizer chip that can be placed inside the catheter tip to convert analog measurements into digital data. The chip contains a 32‑channel digitizer array and a digital back‑end that stores and processes data before transmitting it through a high-speed digital cable. Digitizers like this are common in modern devices, but building one small and low-power enough to operate inside the heart remains a major engineering challenge. Overcoming this could improve image quality, standardize system interfaces, and reduce the overall cost of ICE catheters.
Core building blocks
To assess the feasibility and limitations of such a system, Pelzers designed and integrated the core building blocks: an analog front end, an analog‑to‑digital converter, and power‑supply regulation. Each component already approaches the current state of the art. However, the main contribution lies in designing them so they work together exceptionally well. Smart system‑level choices, innovative techniques, and clever integration result in a power‑efficient, compact chip that provides direction for future commercial ICE catheter designs.
Title of PhD thesis: Supervisors: Dr. Pieter Harpe and Prof. Eugenio Cantatore.