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A Fully Integrated Shape-transformable Wearable Ultrasound Helmet
Ultrasound helmets are typically used to focus ultrasound on specific regions of the brain to treat tremors. To date, most ultrasound helmets that have been developed are bulky and rigid, have suboptimal resolution, and produce considerable heat. Ultrasound arrays on flexible sheets offer an exciting new direction, but their application has so far been limited to monitoring. Importantly, no current systems are designed for manipulating microrobots within a 3D vasculature.
Keywords: Wearable, Micro and nanorobots, ultrasound, electronics, brain, acoustics
We will focus on developing a multifunctional ultrasound helmet composed of an ultrasound transducer array set upon a shape-transformable substrate. This array will allow for the precise, contactless manipulation of ultrasound-actuated microrobots within the intricate 3D blood vessel architecture of the brain. Its design, depicted in Figure, ensures high spatial selectivity and an adaptive acoustic connection. The helmet is comprised of 64-256 triangular modules, representing both fixed (passive) and adjustable (active) units. Each triangular module is equipped with custom-built piezoelectric transducers (5-20 mm, 0.1-2 MHz frequency range) affixed to its lower surface, depicted in Figure. Each fixed unit houses a printed circuit board (PCB) that governs three linear micromotors, which connect with three adjustable units. Additionally, each fixed module interfaces with three others, creating a robust structural network. Collectively, the network is securely adhered to the skin of the skull through a soft bottom layer. The configuration of the modules provides the whole helmet with different transformation modes for different applications; for example, by changing the locations of the fixed modules and the connection relationship of the active modules, buckling deformation of a whole area can be enabled. This design ensures patient comfort and adaptability of the helmet to various head sizes.
Moreover, by tuning the positions of adjustable modules, we can finely tune the acoustic coupling between the corresponding transducer and the skull. Through strategic structure configuration and shape transformation of the triangular modules, we can also alternate between traveling waves and pinpointed ultrasound, enabling dynamic positioning of the focus points. Finally, this novel shape-transformable helmet also possesses the following advantages: 1) It can be freely assembled, disassembled, and scaled up, allowing easy adaptation to different model organisms; and 2) The selective, programmable, and addressable shape-shifting supports the integration of AI modulation for further intelligent manipulation
We will focus on developing a multifunctional ultrasound helmet composed of an ultrasound transducer array set upon a shape-transformable substrate. This array will allow for the precise, contactless manipulation of ultrasound-actuated microrobots within the intricate 3D blood vessel architecture of the brain. Its design, depicted in Figure, ensures high spatial selectivity and an adaptive acoustic connection. The helmet is comprised of 64-256 triangular modules, representing both fixed (passive) and adjustable (active) units. Each triangular module is equipped with custom-built piezoelectric transducers (5-20 mm, 0.1-2 MHz frequency range) affixed to its lower surface, depicted in Figure. Each fixed unit houses a printed circuit board (PCB) that governs three linear micromotors, which connect with three adjustable units. Additionally, each fixed module interfaces with three others, creating a robust structural network. Collectively, the network is securely adhered to the skin of the skull through a soft bottom layer. The configuration of the modules provides the whole helmet with different transformation modes for different applications; for example, by changing the locations of the fixed modules and the connection relationship of the active modules, buckling deformation of a whole area can be enabled. This design ensures patient comfort and adaptability of the helmet to various head sizes.
Moreover, by tuning the positions of adjustable modules, we can finely tune the acoustic coupling between the corresponding transducer and the skull. Through strategic structure configuration and shape transformation of the triangular modules, we can also alternate between traveling waves and pinpointed ultrasound, enabling dynamic positioning of the focus points. Finally, this novel shape-transformable helmet also possesses the following advantages: 1) It can be freely assembled, disassembled, and scaled up, allowing easy adaptation to different model organisms; and 2) The selective, programmable, and addressable shape-shifting supports the integration of AI modulation for further intelligent manipulation
Fabrication of the transformable helmet. The ARSL group has extensive expertise in microfabrication and is able to independently carry out the entire design and fabrication process. The size range of triangle modules (5-30 mm) reflects the surface area of the human skull (100-200 cm2) and the aim to integrate 64-256 transducers. To reduce reflection of sound waves, we plan to fabricate the modules with aluminium sheets serving as the perfect matching layer. Sheet thickness will be selected according to the transducer excitation frequency. The PCB constitutes the entire local control system: unit controller, motor control module, pressure sensor, temperature sensor, and other required sensors and chips. Power will be provided to the PCBs by a common external battery. Commercially available micromotors with diameter 4-10 mm, selected according to module size, will be utilized for actuation. The transducer array will be constructed from commercial circular transducer pieces with suitable resonant Q-factors and resonant impedance. The transducer type is not constrained, and we can also fabricate special transducers, such as LiNbO3 transducers with special interdigital electrode (IDT) patterns, using the cleanroom located in the Binnig and Rohrer Nanotechnology Center.
Fabrication of the transformable helmet. The ARSL group has extensive expertise in microfabrication and is able to independently carry out the entire design and fabrication process. The size range of triangle modules (5-30 mm) reflects the surface area of the human skull (100-200 cm2) and the aim to integrate 64-256 transducers. To reduce reflection of sound waves, we plan to fabricate the modules with aluminium sheets serving as the perfect matching layer. Sheet thickness will be selected according to the transducer excitation frequency. The PCB constitutes the entire local control system: unit controller, motor control module, pressure sensor, temperature sensor, and other required sensors and chips. Power will be provided to the PCBs by a common external battery. Commercially available micromotors with diameter 4-10 mm, selected according to module size, will be utilized for actuation. The transducer array will be constructed from commercial circular transducer pieces with suitable resonant Q-factors and resonant impedance. The transducer type is not constrained, and we can also fabricate special transducers, such as LiNbO3 transducers with special interdigital electrode (IDT) patterns, using the cleanroom located in the Binnig and Rohrer Nanotechnology Center.