Biosensor
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Attachable Skin Monitors that Wick the Sweat Away
- A silicone membrane for wearable devices is more comfortable and breathable thanks to better-sized pores made with the help of citric acid crystals. -
A new preparation technique fabricates thin, silicone-based patches that rapidly wick water away from the skin. The technique could reduce the redness and itching caused by wearable biosensors that trap sweat beneath them. The technique was developed by bioengineer and professor Young-Ho Cho and his colleagues at KAIST and reported in the journal Scientific Reports last month.
“Wearable bioelectronics are becoming more attractive for the day-to-day monitoring of biological compounds found in sweat, like hormones or glucose, as well as body temperature, heart rate, and energy expenditure,” Professor Cho explained. “But currently available materials can cause skin irritation, so scientists are looking for ways to improve them,” he added.
Attachable biosensors often use a silicone-based compound called polydimethylsiloxane (PDMS), as it has a relatively high water vapour transmission rate compared to other materials. Still, this rate is only two-thirds that of skin’s water evaporation rate, meaning sweat still gets trapped underneath it.
Current fabrication approaches mix PDMS with beads or solutes, such as sugars or salts, and then remove them to leave pores in their place. Another technique uses gas to form pores in the material. Each technique has its disadvantages, from being expensive and complex to leaving pores of different sizes.
A team of researchers led by Professor Cho from the KAIST Department of Bio and Brain Engineering was able to form small, uniform pores by crystallizing citric acid in PDMS and then removing the crystals using ethanol. The approach is significantly cheaper than using beads, and leads to 93.2% smaller and 425% more uniformly-sized pores compared to using sugar. Importantly, the membrane transmits water vapour 2.2 times faster than human skin.
The team tested their membrane on human skin for seven days and found that it caused only minor redness and no itching, whereas a non-porous PDMS membrane did.
Professor Cho said, “Our method could be used to fabricate porous PDMS membranes for skin-attachable devices used for daily monitoring of physiological signals.”
“We next plan to modify our membrane so it can be more readily attached to and removed from skin,” he added.
This work was supported by the Ministry of Trade, Industry and Energy (MOTIE) of Korea under the Alchemist Project.
Image description:
Smaller, more uniformly-sized pores are made in the PDMS membrane by mixing PDMS, toluene, citric acid, and ethanol. Toluene dilutes PDMS so it can easily mix with the other two constituents. Toluene and ethanol are then evaporated, which causes the citric acid to crystallize within the PDMS material. The mixture is placed in a mould where it solidifies into a thin film. The crystals are then removed using ethanol, leaving pores in their place.
Image credit:
Professor Young-Ho Cho, KAIST
Image usage restrictions:
News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only.
Publication:
Yoon, S, et al. (2021) Wearable porous PDMS layer of high moisture permeability for skin trouble reduction. Scientific Reports 11, Article No. 938. Available online at https://doi.org/10.1038/s41598-020-78580-z
Profile:
Young-Ho Cho, Ph.D
Professor
mems@kaist.ac.kr
https://mems.kaist.ac.kr
NanoSentuating Systems Laboratory
Department of Bio and Brain Engineering
https://kaist.ac.kr
Korea Advanced Institute of Science and Technology (KAIST)
Daejeon, Republic of Korea
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2021.02.22 View 10902 -
Blood-Based Multiplexed Diagnostic Sensor Helps to Accurately Detect Alzheimer’s Disease
A research team at KAIST reported clinically accurate multiplexed electrical biosensor for detecting Alzheimer’s disease by measuring its core biomarkers using densely aligned carbon nanotubes.
Alzheimer’s disease is the most prevalent neurodegenerative disorder, affecting one in ten aged over 65 years. Early diagnosis can reduce the risk of suffering the disease by one-third, according to recent reports. However, its early diagnosis remains challenging due to the low accuracy but high cost of diagnosis.
Research team led by Professors Chan Beum Park and Steve Park described an ultrasensitive detection of multiple Alzheimer's disease core biomarker in human plasma. The team have designed the sensor array by employing a densely aligned single-walled carbon nanotube thin films as a transducer.
The representative biomarkers of Alzheimer's disease are beta-amyloid42, beta-amyloid40, total tau protein, phosphorylated tau protein and the concentrations of these biomarkers in human plasma are directly correlated with the pathology of Alzheimer’s disease.
The research team developed a highly sensitive resistive biosensor based on densely aligned carbon nanotubes fabricated by Langmuir-Blodgett method with a low manufacturing cost.
Aligned carbon nanotubes with high density minimizes the tube-to-tube junction resistance compared with randomly distributed carbon nanotubes, which leads to the improvement of sensor sensitivity. To be more specific, this resistive sensor with densely aligned carbon nanotubes exhibits a sensitivity over 100 times higher than that of conventional carbon nanotube-based biosensors.
By measuring the concentrations of four Alzheimer’s disease biomarkers simultaneously Alzheimer patients can be discriminated from health controls with an average sensitivity of 90.0%, a selectivity of 90.0% and an average accuracy of 88.6%.
This work, titled “Clinically accurate diagnosis of Alzheimer’s disease via multiplexed sensing of core biomarkers in human plasma”, were published in Nature Communications on January 8th 2020. The authors include PhD candidate Kayoung Kim and MS candidate Min-Ji Kim.
Professor Steve Park said, “This study was conducted on patients who are already confirmed with Alzheimer’s Disease. For further use in practical setting, it is necessary to test the patients with mild cognitive impairment.” He also emphasized that, “It is essential to establish a nationwide infrastructure, such as mild cognitive impairment cohort study and a dementia cohort study. This would enable the establishment of world-wide research network, and will help various private and public institutions.”
This research was supported by the Ministry of Science and ICT, Human Resource Bank of Chungnam National University Hospital and Chungbuk National University Hospital.
< A schematic diagram of a high-density aligned carbon nanotube-based resistive sensor that distinguishes patients with Alzheimer’s Disease by measuring the concentration of four biomarkers in the blood. >
Profile:
Professor Steve Park
stevepark@kaist.ac.kr
Department of Materials Science and Engineering
http://steveparklab.kaist.ac.kr/
KAIST
Profile:
Professor Chan Beum Park
parkcb at kaist.ac.kr
Department of Materials Science and Engineering
http://biomaterials.kaist.ac.kr/
KAIST
2020.02.07 View 8955 -
Professor Hyun Gyu Park Appointed as Associate Editor for Biosensors and Bioelectronics
Professor Hyun Gyu Park from the Department of Chemical and Biomolecular Engineering was appointed as an associate editor for Biosensors and Bioelectronics, an international journal published by Elsevier.
Biosensors and Bioelectronics is one of the top SCI journals in the fields of chemistry and analytical science (IF 9.518 as of 2018). Professor Park was recognized and appointed as the associate editor for this journal due to his outstanding research achievements in the fields of nucleic acid engineering, biosensors, and nanobiotechnology.
Professor Park will serve as the associate editor from this October until December 2021.
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2019.10.01 View 5775 -
Dr. Hyundoo Hwang Receives a Tenured Position at Monterrey Institute of Technology and Higher Education
Hyundoo Hwang, a former graduate student in the Department of Bio & Brain Engineering at KAIST, has been granted a tenured position at the Monterrey Institute of Technology and Higher Education (ITSEM), Mexico.
Dr. Hwang received his bachelor’s, master’s, and doctoral degree at KAIST and started his professorship at Ulsan National Institute of Science & Technology (UNIST) in Korea. He continued his research in the United States as a professor at Georgia Institute of Technology. He has been acknowledged for the development of an advanced nanotechnology for the diagnosis of rare diseases and research in cell signals. He is one of the leading researchers in an international research project in microelectromechanical systems (MEMS) with participation by researchers from over ten countries. He has been active in commercializing biosensor technology in the U.S. and Mexico.
Since its establishment in 1943, ITSEM has grown to 33 campuses in 25 cities in Mexico. It is the largest university in Latin America with over 90,000 students (47% of its graduate students has oversea research experience). It recruits over 5,000 international students and professors every year.
Dr. Hwang will begin teaching at ITSEM as a professor in the Department of Biomedical Engineering (Ingeniería Biomédica) this fall. He will also conduct research in nano- and micro-technology as a member of Sensors and Devices research group.
Professor Gwang Hyun Cho, head of KAIST's Department of Bio and Brain Engineering said that Dr. Hwang’s tenure professorship at ITSEM demonstrated that the academic program at KAIST—from undergraduate to doctoral—was on par with the international standard. He hoped that more talents from the department would seek academic careers in internationally renowned universities around the world.
2015.08.13 View 5768 -
Professor Choi Chul Hui appointed as editor-in-chief of Nanobiosensors in a disease diagnosis magazine
Professor Choi Chul Hui of the Department of Biological and Brain Engineering has been appointed the editor-in-chief of Nanobiosensors, an international medical magazine that concentrates on disease diagnosis.
As the editor-in-chief, Professor Choi will be involved in dissertation evaluations and overall direction of the magazine.
Professor Choi is one of the leading authorities in the field of clinical medicine and has published 60 SCI level dissertations in the fields of cell biology, computational biology, and bio-optics.
He is also the executive director of the KAIST BioImaging Research Center, and his research lab focuses on cell signals and bio imaging. Professor Choi is researching the generation process of degenerative diseases like arteriosclerosis by taking a multidisciplinary approach.
Professor Choi has recently developed a new bio imaging technique that allows for the measurement of perfusion and a new technology for the drug delivery to nerves using ultra short wavelength laser beams.
2011.10.10 View 9787 -
Artificial Spore Production Technology Developed
The core technology needed in the development of ‘biosensors’ so crucial in diagnosing illnesses or pathogens was developed by Korean research team.
KAIST’s Professor Choi In Seung of the department of Chemistry developed the technology that allows for the production of Artificial Spore by selectively coating a live cell.
In the field of engineering the problem in developing the next generation bio sensor, the cell based sensor, was that it was difficult to keep a cell alive without division for a long time. Once a cell is taken out of the body, it will either divide or die easily.
Professor Choi’s research team mimicked the spore, which has the capability to survive harsh conditions without division, and chemically coated a live cell and artificially created a cell similar to that of a spore.
The physical and biological stabilities of the cell increased by coating an artificial shell over the yeast cell. The shell is composed with a protein similar to that of the protein that gives mussels its stickiness. In addition by controlling the thickness of the shell, the division rate of the yeast can be controlled.
Professor Choi commented that this technology will serve as the basis for the single cell based biosensor.
The research was conducted together with Professor Lee Hae Shin of KAIST department of Chemistry and Professor Jeong Taek Dong of Seoul National University’s department of Chemistry and was published as the cover paper of ‘Journal of the American Chemical Society’.
2011.04.01 View 11869