CUHK researchers, led by Professors Zhang Li, Philip Chiu Wai-yan, and Tony Chan Kai-fung, have developed wirelessly powered electronic stents for a non-invasive electrical stimulation therapy to treat gastric acid reflux. The research was published in Science Advances and will be featured in Nature Reviews Bioengineering’s April 2023 issue.
GERD is a persistent gastrointestinal disorder with widespread prevalence. Medication is necessary for about 8% of patients, but it can harm their physical and mental health. Surgical interventions such as Nissen fundoplication and magnetic augmentation are available but require laparoscopic surgery. Electrical stimulation of the lower oesophageal sphincter (LES) offers a promising solution but requires invasive surgery, which is risky.
Implantable electrical stimulation systems for GERD have significant surgical burdens and potential risks, making them difficult to implement. As GERD patients become more prevalent worldwide, there is a strong need for a less invasive electrical stimulation system that can reduce surgical risks and increase patient acceptance.
The research team has developed a wirelessly powered electronic stent (E-Stent) that provides a less invasive strategy for diagnosis and treatment in the gastrointestinal tract. The E-Stent uses a super elastic clinical oesophageal stent as the mechanical skeleton, a liquid metal antenna, and an intrinsically stretchable pulse generator. The liquid metal has a low melting temperature and high electrical conductivity, making it compliant with deformations in the oesophagus. With a wearable power transfer system, the elastic antenna can harvest sufficient energy for electrical stimulation therapy, even under compression of the oesophagus.
To improve design flexibility and speed up production, the research team utilised a laser engrafting machine for the batch fabrication of stretchable circuits. The circuit’s intrinsic stretchability and excellent mechanical properties enable it to provide stable biphasic current stimulation under various extreme deformations. The E-Stent not only overcomes the power bottleneck of bioelectronic implants but also has the potential for other non-invasive biomedical applications in organs with a natural orifice.
The Director of the Chow Yuk Ho Technology Centre for Innovative Medicine, CU Medicine stated that the team’s bioelectronic platform can regulate GERD by electrical stimulation. The researchers demonstrated the concept in pig models, showing that continuous electrical stimulation can increase the pressure on the lower oesophageal sphincter, which could potentially prevent gastric acid in a less invasive way. The team’s next step is to optimise and transform the prototypes into clinical products. They will continue their interdisciplinary collaboration to move forward with the work and help more people.
Professor Zhang Li from the Department of Mechanical and Automation Engineering collaborated with CU Medicine to develop the E-Stent platform and a transoral delivery strategy to overcome several challenges in mucosa-interfacing bioelectronics.
The team worked to address issues such as wirelessly powering bioelectronics inside the body, especially for high-power applications like electrical stimulation, and designing microneedle electrodes to safely and efficiently deliver electrical stimulation across the mucosa, which acts as a natural barrier protecting the GI tract.
Research Assistant Professor Tony Chan Kai-fung of the Chow Yuk Ho Technology Centre for Innovative Medicine expressed that digital medicine could have a transformative impact and demonstrates the clinical potential to integrate other functions. He suggested that pressure sensors and other bio-sensors could be integrated with the E-Stent for physiological assessment.
The data collected could be used for real-time optimisation of electrical stimulation and personalised treatment. Professor Chan also noted that the applications of the E-Stent platform are not limited to GERD but can be extended to other parts of the gastrointestinal tract and organs with natural orifices.
Currently, the research team is collaborating to add new features to the E-Stent for other applications in the gastrointestinal tract and conducting further preclinical and clinical evaluations. The team aims to develop a non-invasive platform that provides efficient and safe options for personalised treatments and physiological assessments with various functions of high clinical value. The team envisions that the E-Stent will have a promising future as a highly useful technology.
