Receive KAIST news by email!
Type your e-mail address here.
by recently order
by view order
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 email@example.com 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
Stretchable Multi-functional Fiber for Energy Harvesting and Strain Sensing
(from left: Professor Steve Park, Jeongjae Ryu and Professor Seungbum Hong) Fiber-based electronics are expected to play a vital role in next-generation wearable electronics. Woven into textiles, they can provide higher durability, comfort, and integrated multi-functionality. A KAIST team has developed a stretchable multi-functional fiber (SMF) that can harvest energy and detect strain, which can be applied to future wearable electronics. With wearable electronics, health and physical conditions can be assessed by analyzing biological signals from the human body, such as pulse and muscle movements. Fibers are highly suitable for future wearable electronics because they can be easily integrated into textiles, which are designed to be conformable to curvilinear surfaces and comfortable to wear. Moreover, their weave structures offer support that makes them resistant to fatigue. Many research groups have developed fiber-based strain sensors to sense external biological signals. However, their sensitivities were relatively low. The applicability of wearable devices is currently limited by their power source, as the size, weight, and lifetime of the battery lessens their versatility. Harvesting mechanical energy from the human body is a promising solution to overcome such limitations by utilizing various types of motions like bending, stretching, and pressing. However, previously reported, fiber-based energy harvesters were not stretchable and could not fully harvest the available mechanical energy. Professor Seungbum Hong and Professor Steve Park from the Department of Materials Science and Engineering and their team fabricated a stretchable fiber by using a ferroelectric layer composed of P(VDF-TrFE)/PDMS sandwiched between stretchable electrodes composed of a composite of multi-walled carbon nanotubes (MWCNT) and poly 3,4-ethylenedioxythiophene polystyrenesulfonate (PEDOT:PSS). Cracks formed in MWCNT/PEDOT:PSS layer help the fiber show high sensitivity compared to the previously reported fiber strain sensors. Furthermore, the new fiber can harvest mechanical energy under various mechanical stimuli such as stretching, tapping, and injecting water into the fiber using the piezoelectric effect of the P(VDF-TrFE)/PDMS layer. Professor Hong said, “This new fiber has various functionalities and makes the device simple and compact. It is a core technology for developing wearable devices with energy harvesting and strain sensing capabilities.” This article, led by PhD candidate Jeongjae Ryu, was published in the January 2019 issue of Nano Energy. Figure 1.Schematic illustration of an SMF fiber and its piezoelectric voltage output and response to strain. Figure 2. Photographs of a stretchable multi-functional fiber being stretched by 100%, bent, and twisted.
Controlling Crystal Size of Organic Semiconductors
A KAIST research team led by Professor Steve Park from the Department of Materials Science and Engineering Recently, solution-processable organic semiconductors are being highlighted for their potential application in printed electronics, becoming a feasible technique to fabricate large-area flexible thin film at a low cost. The field-effect mobility of small-molecule organic semiconductors is dependent on the crystallinity, crystal orientation, and crystal size. A variety of solution-based coating techniques, such as ink-jet printing, dip-coating, and solution shearing have been developed to control the crystallinity and crystal orientation, but a method for developing techniques to increase the crystal size of organic semiconductors is still needed. To overcome this issue, the research team developed an inorganic polymer micropillar-based solution shearing system to increase the crystal size of an organic semiconductor with pillar size. Using this technique, the crystallization process of organic semiconductors can be controlled precisely, and therefore large-area organic semiconductor thin film with controlled crystallinity can be fabricated. A variety of solution-based coating techniques cannot control the fluid-flow of solutions appropriately, so the solvent evaporates randomly onto the substrate, which has difficulty in the fabrication of organic semiconductor thin film with a large crystal size. The research team integrated inorganic polymer microstructures into the solution shearing blade to solve this issue. The inorganic polymer can easily be microstructured via conventional molding techniques, has high mechanical durability, and organic solvent resistance. Using the inorganic polymer-based microstructure blade, the research team controlled the size of small molecule organic semiconductors by tuning the shape and dimensions of the microstructure. The microstructures in the blade induce the sharp curvature regions in the meniscus line that formed between the shearing blade and the substrate, and therefore nucleation and crystal growth can be regulated. Hence, the research team fabricated organic semiconductor thin-film with large crystals, which increases the field-effect mobility. The research team also demonstrated a solution shearing process on a curved surface by using a flexible inorganic polymer-based shearing blade, which expands the applicability of solution shearing. Professor Park said, “Our new solution shearing system can control the crystallization process precisely during solvent evaporation.” He added, “This technique adds another key parameter that can be utilized to tune the property of thin films and opens up a wide variety of new applications. The results of this work entitled “Inorganic Polymer Micropillar-Based Solution Shearing of Large-Area Organic Semiconductor Thin Films with Pillar-Size-Dependent Crystal Size” was published in the July 2018 issue of Advanced Materials as a cover article.
Spray Coated Tactile Sensor on a 3-D Surface for Robotic Skin
Robots will be able to conduct a wide variety of tasks as well as humans if they can be given tactile sensing capabilities. A KAIST research team has reported a stretchable pressure insensitive strain sensor by using an all solution-based process. The solution-based process is easily scalable to accommodate for large areas and can be coated as a thin-film on 3-dimensional irregularly shaped objects via spray coating. These conditions make their processing technique unique and highly suitable for robotic electronic skin or wearable electronic applications. The making of electronic skin to mimic the tactile sensing properties of human skin is an active area of research for various applications such as wearable electronics, robotics, and prosthetics. One of the major challenges in electronic skin research is differentiating various external stimuli, particularly between strain and pressure. Another issue is uniformly depositing electrical skin on 3-dimensional irregularly shaped objects. To overcome these issues, the research team led by Professor Steve Park from the Department of Materials Science and Engineering and Professor Jung Kim from the Department of Mechanical Engineering developed electronic skin that can be uniformly coated on 3-dimensional surfaces and distinguish mechanical stimuli. The new electronic skin can also distinguish mechanical stimuli analogous to human skin. The structure of the electronic skin was designed to respond differently under applied pressure and strain. Under applied strain, conducting pathways undergo significant conformational changes, considerably changing the resistance. On the other hand, under applied pressure, negligible conformational change in the conducting pathway occurs; e-skin is therefore non-responsive to pressure. The research team is currently working on strain insensitive pressure sensors to use with the developed strain sensors. The research team also spatially mapped the local strain without the use of patterned electrode arrays utilizing electrical impedance tomography (EIT). By using EIT, it is possible to minimize the number of electrodes, increase durability, and enable facile fabrication onto 3-dimensional surfaces. Professor Park said, “Our electronic skin can be mass produced at a low cost and can easily be coated onto complex 3-dimensional surfaces. It is a key technology that can bring us closer to the commercialization of electronic skin for various applications in the near future.” The result of this work entitled “Pressure Insensitive Strain Sensor with Facile Solution-based Process for Tactile Sensing Applications” was published in the August issue of ACS Nano as a cover article. (Figure: Detecting mechanical stimuli using electrical impedance tomography.)
마지막 페이지 1
KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Copyright(C) 2020, Korea Advanced Institute of Science and Technology,
All Rights Reserved.