Cornell University Researchers Develop Controllable Hydrogen Microbubble Chip System with Drug Delivery Potential

Researchers at Cornell University have developed a chip-based system capable of generating and controlling hydrogen microbubbles on demand. By directing the bubbles to manipulate fluid flow, this technology holds promise for advancements in applications such as targeted drug delivery. In experiments, they harnessed the power of ultrasound to energize bubbles located in a 3 millimeter area on the chip, controlling the flow of liquid. The device generates these bubbles on an electrode grid, enabling power control.

Real-Time Programming Capability of the System

The newly established system can be programmed in real-time, allowing researchers to precisely generate individual bubbles at desired times and locations, control their size and quantity, and guide them electronically. They can control the movement of the bubbles, whether individually or in larger groups, enabling them to direct fluid flow on demand. According to the researchers, this technology could play a role in medical applications, as it paves the way for creating reconfigurable microfluidic devices that enable precise drug delivery. "With this bubble array, we can control the size, number, and position of the bubbles in real-time, allowing us to program the direction of flow," said Zhang Zhiyuan, one of the authors of the new study published in the journal Science Advances.

The size of the bubbles determines the flow of liquid. Zhang Zhiyuan used a chip manufactured at Cornell's Nanoscience and Technology Facility, which consists of nine small electrodes arranged in a square, capable of generating bubbles with diameters ranging from 10 micrometers to 100 micrometers. To create a hydrogen bubble, he decomposed water molecules using electricity. If the voltage is applied for a longer duration, the bubbles become larger. After generating the bubbles, the researchers exposed the system to acoustic energy, with ultrasound causing the bubbles to resonate, creating vibrations that drive the surrounding liquid flow.

Relationship Between Bubble Size and Flow

The researchers noted that the size of the bubbles is crucial when controlling fluid flow. The size of the bubbles determines the required resonant ultrasound frequency. Properly matched frequencies produce strong fluid flow. They added, "The size of the bubbles determines the resonant frequency of the bubbles." Ithai Cohen, a professor in the Department of Physics at Cornell University, stated, "If you apply ultrasound at a frequency of 40 kHz and the bubbles are too small or too large, they won't oscillate significantly. But if their size is just right to resonate at 40 kHz, then you will generate a substantial flow."

Research indicates that flow can be generated through single or multiple bubbles. When a single bubble is tuned to resonance, it creates flow by transferring energy to the adjacent liquid. When multiple bubbles work together, they produce symmetrical flow when their sizes are the same. Experiments showed that when the bubble sizes differ, the largest bubble dominates the flow direction. The researchers stated that by changing the position of the bubbles, programmable movement can also be achieved, shifting flow from left to right or guiding movement along a curve by arranging five bubbles in an L-shape. Similarly, they can adjust the flow by varying the voltage.

They found that higher voltage generates a cloud of bubbles in rapid flow. Therefore, they only need to turn on the ultrasound to propel the bubbles in a specific direction.

Application Potential of Controllable Hydrogen Microbubble Technology

The development of this technology marks a significant advancement in microfluidic devices, enabling precise drug delivery. By precisely controlling the generation and movement of bubbles, researchers can create more flexible solutions for medical applications. Furthermore, the programmability of this technology makes it more feasible for use in various contexts, thereby enhancing the accuracy and efficiency of medical treatments.