Scientists have created a transparent, biocompatible ultrasound transducer chip that resembles a microscope glass slide that can insert into an optical microscope
Ultrasound scans can also be used to stimulate cells and direct cell function. Penn State researchers have developed an easier, more effective way to harness the technology for biomedical applications.
The chip allows for easier viewing and may be used in the future development of stem cell, cancer and neuroscience research. Cells can be cultured and stimulated directly on top of the transducer chip and the resulting changes can be imaged with optical microscopy techniques.
The researchers reduced the ultrasound stimulation set up by creating a transparent transducer platform made of a piezoelectric lithium niobate material. Piezoelectric materials generate mechanical energy when an electric voltage is applied.
The chip’s biocompatible surface allows the cells to be cultured directly on the transducer and used in repeated stimulation experiments over several weeks.
The transducer emits ultrasound waves, which pulse the cells and trigger ion influx and outflux when connected to a power source. In order to test this, the team set up cultured bladder cells on the chip before inserting fluorescent calcium indicators into the cells to show changes in calcium signalling under the microscope during stimulation.
The findings of the bladder cancer cell study can be used in future applications such as stem cell differentiation, mechanosensitive neuromodulation, drug delivery and the opening of the blood-brain barrier.
Sri-Rajasekhar “Raj” Kothapalli, assistant professor of biomedical engineering at Penn State said: “In the conventional ultrasound stimulation experiments, a cell culture dish is placed in a water bath, and a bulky ultrasound transducer directs the ultrasound waves to the cells through the water medium.
This was a complex setup that didn’t provide reproducible results: The results that one group saw another did not, even while using the same parameters because there are several things that could affect the cells’ survival and stimulation while they are in the water, as well as how we visualize them.”
Kothapalli added: “Since the cells are directly sitting on the transparent transducer surface, we can confirm that all the cells are equally stimulated at the same time using a single ultrasound stimulus, unlike conventional approaches,”
“And unlike earlier processes, we can get high resolution images of many cells at once in a single field of view, because we are able to see the cells from a close distance.”
The ultrasound stimulation chip is low-cost, easy to construct, compact and reusable. It is also disposable and scalable in size.
Haoyang Chen, the first author of the paper said: “It is easy to grow cells on the chip using standard cell culturing methods,” Chen said. “The setup provides controllable stimulation parameters for a variety of experiments and can be imaged with all conventional optical microscopy techniques.”
