한빛사 인터뷰
1. Can you please briefly summarize the paper?
Real-time, continuous, and precise monitoring of vital signs in vivo is essential for detecting early signs of dysfunction of the organs and enabling timely intervention. For example, conditions like acute ischemic stroke constitute 87% of all stroke cases and post-surgical atrial fibrillation occurs in 20-50% of patients after cardiac surgery, underscore the critical need for predictive monitoring of these organs. However, current solutions struggle to balance mechanical mismatches with living tissues, patient comfort, and unobtrusive signal acquisition. On the other hand, surgical intervention is required to remove the implants after their use, which leads to medical complications and additional costs.
Through this work, we addressed those shortcomings by developing (i) A biodegradable passive tag implant comprising a coil antenna and a nanoscale crack-based resistive strain gauge sensor, and (ii) A wearable reader patch for interrogating with the implanted passive tag and sending the sensor response to the peripheral devices. The passive tag incorporates gelatin-ionic liquid substrate (GIS) that allows resonance tuning to operate the system in a detuned mode of < 100 MHz by controlling the amount of ionic liquid. Besides, the wireless sensing is based on load modulation where the strain gauge sensor response is reflected in the readout antenna carrier frequency through biodegradable coil antenna in terms of the amplitude variation and this variation can be detected and processed by simple electronic circuit in the form of an envelope detector. Therefore, we leveraged two modes of communication (i) near field inductive coupling to couple reader coil antenna with the subcutaneously implanted biodegradable coil antenna and (ii) Bluetooth communication for far field sensory data transfer. We successfully validated a proof-of-concept through a series of ex vivo and in vivo experiments including real-time signal acquisition of the superimposed vital signs (heart rate and the respiration rate) in a living rat model, and the biocompatibility of the associated materials for realizing a passive tag. Thus, the proposed system is a low-cost alternative to the state-of-the-art in vivo signal acquisition systems utilizing bulky and expensive benchtop devices like network analyzers to measure the changes in resonance frequency.
Figure: Illustration of the proposed system for fully wireless, in vivo assessment of superimposed vital signs by incorporating a biodegradable passive tag interrogated with a wearable reader patch. By post-processing the wirelessly acquired signal, the organ-specific response can be retrieved.
2. Can you please tell us the main difficulties you had in the laboratory work and how you overcame them?
There were certainly many challenges to overcome. A research laboratory often lacks all the desired facilities, especially for multidisciplinary work like this. One major challenge is sourcing appropriate materials and developing the necessary methodologies, as well as securing the right fabrication equipment, either within the lab or through external resources. For example, in this work, I initially experimented with several methods, such as lithography and deposition, to fabricate a biodegradable coil antenna. However, using metal foils and laser patterning significantly enhanced performance and saved time. Despite having a clear outline of the work, experimental results are often unpredictable, and identifying the root cause of issues can be time-consuming. Additionally, strong collaboration is essential for progress, fostering constructive discussions, and effectively tackling these challenges together.
3. Please introduce your laboratory, university or organization to bio-researchers in Korea.
The Wearable and Implantable Soft Electronics (WISE) Laboratory, led by Prof. Tae-il Kim at Sungkyunkwan University in Suwon, Korea, focuses on cutting-edge interdisciplinary research that bridges materials science, bioengineering, and nanotechnology. The lab is dedicated to developing advanced biomaterials, microfabrication techniques, and novel devices to address complex challenges in the biomedical field. The research is organized into three main areas: (i) noise-free bioelectronics, (ii) flexible and stretchable electronics, and (iii) bio-inspired and bio-integrated electronics.
Furthermore, the WISE lab brings together a diverse mix of national and international researchers, fostering strong academic and industry collaborations, and is well-equipped to drive advanced research and innovation in the field of future bioelectronics.
Figure: Members of the Wearable and Implantable Soft Electronics laboratory (Prof. Tae-il Kim’s Research Group, https://sites.google.com/site/taeilkimslab) at Sungkyunkwan University.
I would like to take this opportunity to express my heartfelt gratitude to my supervisor, Prof. Tae-il Kim, and all my lab members for their unwavering support in helping me accomplish this project. I am also deeply grateful to my collaborators from the Laboratory of Cell and Tissue Engineering in the School of Chemical Engineering at Sungkyunkwan University, led by Prof. Suk Ho Bhang.
Figure (from left): Prof. Tae-il Kim (Wearable and Implantable Soft Electronics Lab, SKKU), Prof. Suk Ho Bhang (Laboratory of Cell and Tissue Engineering, SKKU), myself, and Dong-Hyun Lee (Co-first author, Laboratory of Cell and Tissue Engineering, SKKU).
4. Please tell us your experiences and your thoughts related to research activities abroad.
Research activities abroad offer both advantages and challenges and having spent over a decade conducting research in Korea, I have gained valuable insights into these dynamics. Many research labs in Korea, especially in science and technology fields, are well-resourced and emphasize collaboration, which supports researchers in exploring their full potential. Timeless access to advanced facilities and equipment allows for efficient planning and execution of experiments, which can help in achieving a high standard of research output.
However, maximizing these resources requires a careful balance, as it’s essential to be strategic about work commitments to maintain a healthy work-life balance. Success in an international research environment often depends on various personal and professional factors, such as the lab’s culture, and one's own adaptability and personality. When these elements align, they create a supportive atmosphere that fosters both professional growth and personal well-being, making the experience rewarding and fulfilling.
On the other hand, missing aspects of your own family and relatives, culture, festivals, food as well as dealing with language barriers, can sometimes be distractions while working abroad. Cultural differences in work habits, communication styles, and even day-to-day interactions can occasionally make it challenging to stay fully focused on your research. Language issues, especially in non-English-speaking countries like Korea, can further complicate communication, collaboration, and understanding, which may slow down progress and require additional effort to overcome.
5. Can you provide some advice for younger scientists who have plans to study abroad?
As I mentioned earlier, studying abroad presents both significant opportunities and challenges. To maximize the opportunities, it's essential to be proactive in managing potential obstacles. One key piece of advice is to never compromise on the quality of the research environment, including the lab culture, resources, and the expertise of your supervisor. These factors play a crucial role in your success as a scientist. If possible, reach out to current or former lab members for insights. The right environment can foster growth, while the wrong one may limit it.
Additionally, don't overlook practical aspects like language, food, culture, and weather. Preparing for these secondary factors can ease your transition, allowing you to focus on your academic and professional goals.
To all the scientists, to me research is not just a talent or hard-work. Your personality matters for adaptability under new circumstances and maintaining harmony among your colleagues is essential. Regarding research, even with a well-planned approach, you often encounter unexpected results, requiring time, patience, and persistence to identify and address underlying issues. It’s crucial to stay focused on the main objective, maintaining patience as setbacks arise. Each unexpected result brings a chance to refine hypotheses and strengthen problem-solving skills.
6. Future plan?
After spending considerable time as a full-time researcher in the lab, I’ve come to realize the importance of bridging the gap between research and its real-world applications. I increasingly feel the need to extend my work beyond the laboratory and address practical challenges through translational research. My focus on emerging wearable and implantable bioelectronic devices stems from their potential to provide cost-effective solutions, particularly for underserved populations in developing countries including my home country Nepal. By combining cutting-edge technology with practical, accessible designs, I aim to develop solutions that can improve health outcomes and quality of life in these regions, while contributing to both scientific progress and social impact.
7. Do you have anything else that you would like to tell Korean scientists and students?
Korea has played a crucial role in shaping me as a researcher, and I am deeply grateful for the support of the people and community around me. I envision a bright future for science in Korea, where the experienced scientific community will continue to inspire and shape the innovative minds of the next generation.
#wireless in-vivo monitoring
# superimposed vital signs
# biodegradable passive tag
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