NanoSentuating Systems Laboratory aims to develop the integrated multi-functional NanoSentuating Nano/Micro Elelctro Mechanical Systems(N/MEMS) (Figure), where nanoscale sensing and actuating functions are integrated with intelligent functions in a single chip; thus, achieving the autonomous nanosentuating functions required for high-performance N/MEMS. Laboratory’s key strategy and unique research directions are focused on the invention of a new class of sentuating nanodevices (NT) inspired from biological sentuating organs (BT) for their applications to next-generation information (IT) and medical (MT) systems. Recent topics on the bio-inspired sentuating devices for specific applications include: muscle-inspired cascaded actuators; cognitive tactile transceivers for bi-directional rational and emotional interface; muscle-inspired actuators for biomolecule detection; elbow-inspired rotating optical mirrors; worm-inspired DNA separators; circulation-inspired biomolecule counters and concentration detectors; spleen-inspired lysis devices for cell aging and deformability monitoring; mitochondria-inspired fuel cells for potable power generation; eel-inspired electrolyte batteries for high-voltage electrical power generation; heart-inspired fluidic injectors for digital inkjet printing; etc.
NanoSentuating N/MEMS for Nano-scale Multi-modal Information Carriers
Research Fields and Applications
• Micro/Nano Electromechanical Devices and Applications
Developed are the miniaturized electromechanical digital actuators, such as silicon muscle chips, mechanical digital-to-analog converters, modulators, and manipulators, as well as the inertial microsensors, including accelerometers, gyroscopes and magnetic sensors, combined with electronic circuits and communication modules for applications to automotive electronics, aerospace navigation, computer devices and electronic games.
• Micro/Nano Optomechanical Devices and Applications
Optomechanical mirrors, waveguides, and optical components are combined with light sources, detectors, optical fibers, waveguides, and connectors for applications to high-density information storage and high-speed optical communication systems.
• Micro/Nano Thermo- & Bio-fluidic Devices and Applications
Digital injectors, propulsion devices, fluidic digital-to-analog converters, microfluidic separators, pumps, valves and diffusers are combined with heaters, channels, mixers, and reactors for applications to digital ink-jet printers, pressure regulators, flow controllers, fluidic distributors, biomolecule separators, lab-on-a-chip, and micro total analysis systems.
• Fundamental Technology and Physical Phenomena in Micro/Nano Regime
Fundamental research topics include analysis and design, materials and processes, characterization and evaluation for the phenomena and principle involved in the understanding and invention of multi-modal, multi-scale devices and systems.
I. Skin-attachable Human Emotion Monitoring Systems
(National Research Leader Program)
Sponsor: Ministry of Science and ICT (2017.3~2020.2)
I.1 Human Stress Monitoring for Psychological Health1)
Stress monitoring patch
A human stress monitoring patch, composed of the three kinds of sensors for skin temperature, skin conductance, and pulse wave into the size of a stamp (25mm × 15mm × 72μm), enhances wearing comfort with small skin contact area and high flexibility. The skin contact area is minimized through the invention of an integrated multi-layer structure and the associated microfabrication process; thus, being reduced to 1/125 of that of the conventional single-layer multiple sensors. The flexible pulse wave sensor uses a flexible piezoelectric membrane, supported by a perforated polyimide membrane; thus, increasing overall patch flexibility. The fabricated stress patch measures the skin temperature with the sensitivity of 0.31Ω/°C, the skin conductance with the sensitivity of 0.28μV/0.02μS, and the pulse wave with the response time of 70msec, respectively. The skin-attachable stress patch, capable to detect multimodal bio-signals, shows potential for application to wearable human emotion monitoring systems for use in daily life.
I.2 Human Piloerection Monitoring for Emotional Touch2)
Piloerection monitoring sensor
The piloerection sensors are developed to monitor Human emotional status by measuring the size and density of the goosebumps appeared on Human skins. It is demonstrated experimentally that the interlocking spiral electrodes of the piloerection sensors are effective to measure the goosebumps at the sensitivity of 00252%/μm in the height range of 0~318μm. The flexible sensors show strong potentials for interactive Human emotional communication devices and wearable human-machine cognitive interface.
I.3 Human Sweat Rate Sensors for Thermal Comfort 3)
Wearable Sweat Rate Sensor
A portable sweat rate sensor, integrated with a thermo-pneumatic actuator, is developed for an active and continual monitoring of human thermal status. The portable sweat rate sensor, having a size of 38mm × 41mm × 29mm with a total weight of 63g, is capable to lift the humidity chamber 1.91mm above the skin in the period of 3 min. The sensor measures the sweat rate with the sensitivity of 0.056 (pF/sec)/ (g/m2h) and the linearity of 99.1 % in the sweat rate range of 3.76~137.68 g/m2h. The integrated actuator not only performs the natural sweat ventilation, but also reduces the noise caused by human motions and environmental wind. The portable sweat rate sensor is suitable for long-term human thermal status monitoring.
II. Viable CTC Isolation and Multi-modal CTC Characterization
(Materials & Components Technology Development Program)
Sponsor: Korea Evaluation Institute of Industrial Technology (2017.04 - 2023.12)
The nano-bio-medical convergence research is focused on the cancer diagnosis and prognosis prediction based on the characteristics of circulating tumor cells (CTCs) in patient’s blood. The research and development activities are focused on high-throughput viable CTC isolation, multi-modal CTC characterization, bio-inspired CTC culture and drug response analysis, and their clinical studies.
II.1 Viable CTC Isolation 4)
Viable CTC Isolations
The CTC isolation device are invented with microfabricated tapered-slit filters for high-throughput viable CTC isolation. The heterogeneous CTCs are isolated at the whole blood flow rate of 20 ml/hr, where the capture efficiency of 80%, the recovery rate of 84%, and the viability of 82% are demonstrated experimentally. The CTC isolation devices also reduce the cell stress to the 18% of the conventional devices.
II.2 Multimodal CTC Characterization 5)
[a] Cell Impedance Analysis Chip
[b] Cell Adhesion and Cytotoxicity Analysis Chip
The impedance monitoring microchamber array [a] is capable to measure the individual cell impedance. The long-term and stable cell-to-electrode contacts are maintained by the simple cell allocation process, where 1) Cell mixture is poured in the microchamber array in order to allocate individual cells in each microchamber. 2) A cover is placed on the microchamber array to make individual cells contact with the electrodes in each chamber. Through the impedance analysis, we verified that the cancer cells are clearly distinguishable against the normal cells: cancer cells show the lower resistance (241kΩ vs 271kΩ) and the lower capacitance (3.13nF vs 7.01nF) compared to normal cells. The stepwise cell adhesion chip [b] is invented for the cytotoxic test based on the cell impedance and adhesion analysis. A series of the multiple shear stress levels of 0, 1.2, 1.8, 2.5, 3.1, 3.8 dyne / cm2 are generated by the flow of the 5 % ethanol media. At the shear stress of 2.5 dyne/cm2, the normalized Rcells and Ccells are decreased rapidly; thus, indicating that cell-to-matrix adhesion are decreased and the cell death rates areincreased.
- 1. Sunghyun Yoon, Jai Kyoung Sim, and Young-Ho Cho*, "A Flexible and Wearable Human Stress Monitoring Patch," Scientific Reports, Vol.6, Article No.23468 (March 23, 2016) pp.1-11.
- 2. Jaemin Kim, Dae Geon Seo, and Young-Ho Cho*, "A Flexible Skin Piloerection Monitoring Sensor," Applied Physics Letters, Vol.104, Issue 25, Paper No.253502. (June 23, 2014) pp.1-5.
- 3. Jai Kyoung Sim, Sunghyun Yoon, and Young-Ho Cho*, "Wearable Sweat Rate Sensors for Human Thermal Comfort Monitoring," Scientific Reports, Vol.8, Article No.1181 (Jan. 19, 2018) pp.1-11.
- 4. Yoon-Tae Kang, Il Doh, Jiyoung Byun, Hee-Jin Chang* and Young-Ho Cho*, "Label-free Rapid Viable Enrichment of Circulating Tumor Cell by Photosensitive Polymer-based Microfilter Device," Theranostics, Vol.7, Issue 13 (July 22, 2017) pp.3179-3191
- 5. Yoon-Tae Kang1, Min-Ji Kim1, and Young-Ho Cho*, "A Cell Impedance Measurement Device for the Cytotoxicity Assay Dependent on the Velocity of Supplied Toxic Fluid," Journal of Micromechanics and Microengineering, Vol.28, No.4, Paper No.045012. (April 2018) pp.1-8.