“Co-author Robert Rohling, professor of electrical and computer engineering at UBC, commented: “With this technology, you can shrink these sensors and use them to look at your arteries and veins. They can also be attached to your chest and used in everyday life. continuous monitoring of your heart. This technology opens up many different possibilities.”

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University of British (British) Columbia researcher Carlos Gerardo demonstrates new ultrasonic transducer

In order to make ultrasonic transducers cheaper in the medical market, researchers at the University of British Columbia (UBC) have used polymers instead of traditional silicon materials to design a Capacitive micromachined ultrasound transducers (hereinafter referred to as CMUTs, also known as capacitive MEMS ultrasonic transducers).

The research is detailed in a paper titled “Fabrication and testing of polymer-based capacitive micromachined ultrasound transducers for medical imaging,” published in the journal Microsystems & Nanoengineering. In their paper, the researchers describe how to use more economical materials such as SU-8 photopolymer and Omnicoat instead of silicon to build thin and sensitive ultrasound transducer arrays.

Figure a is a linear array of 64-column poly-CMUT array elements mounted on a PCB; the spacing of the 6-column CMUT array elements in Figure b is 550 μm; the CMUT cells in Figure c can show the mutual interaction between the top electrode and the bottom cavity even

In just six steps and at an estimated unit cost of less than $100, the researchers fabricated a micron-scale biocompatible parylene-sealing polymer CMUT (hereafter referred to as poly-CMUT). The device is a linear array composed of 64 columns of CMUT array elements, each of which contains 4 × 75 CMUT units (ie, plastic MEMS), and the spacing of each array element is 550 μm. Linear arrays allow researchers to conduct precise ultrasound imaging experiments using beamforming techniques.

The key to making these poly-CMUTs is to encapsulate the metal electrodes inside the film rather than on top, enabling thin stacks and low operating voltages similar to conventional CMUTs fabricated from polysilicon or silicon nitride. The researchers report in their paper that the poly-CMUT can be pre-biased to operate as a passive device in reception and have a low excitation voltage (that is, a 12V AC signal superimposed on a 10V DC signal) during ultrasonic transmission.

Another interesting aspect of this research is that its maximum process temperature does not exceed 150°C, which means that these poly-CMUTs can be fabricated directly on silicon-based electronics such as beamformers and Tx/Rx switches. The researchers anticipate that such ultrasonic transceivers could be integrated into flexible substrates for conformal wearable health monitoring systems.

Co-author Robert Rohling, professor of electrical and computer engineering at UBC, commented: “With this technology, you can shrink these sensors and use them to look at your arteries and veins. They can also be attached to your chest and used in everyday life. continuous monitoring of your heart. This technology opens up many different possibilities.”