Creating innovative bio-convergent technologies for better human life

NanoSentuating Systems Laboratory
Young-Ho Cho


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)




A porous PDMS pulsewave sensor with haircell structures



A porous polydimethylsiloxane (PDMS) pulsewave sensor with haircell structures is developed for enhanced water vapor transmission rate (WVTR) and signal-to-noise ratio (SNR). In order to improve WVTR, a porous PDMS layer is fabricated in the thickness of 40 μm with high porosity of 45 % by crystallizing and dissolving citric acid powders in PDMS. On the porous PDMS layer, haircell structures are formed to increase the skin contact area; thus, enhancing SNR. The porous PDMS pulsewave sensor with haircell structures shows the enhanced WVTR of 486.17 g/day/m2 and the SNR of 22.89, respectively, 72 % and 757 % higher than those of the conventional PDMS pulsewave sensors without haircell structures. Furthermore, the enhanced WVTR is 13 % higher than the human skin sweat rate of 432 g/day/m2. The present pulsewave sensor shows strong potential for applications in real-time and long-term pulsewave monitoring with lower skin irritation and enhanced SNR.



I.2 Human Emotion Monitoring Skin Patches without skin trouble2)




Human Emotion Monitoring Skin Patches



The present research proposes the present porous polydimethylsiloxane (PDMS) layer for the skin trouble reduced daily life skin attachable devices. The present research proposes the new pores forming method in the PDMS by crystallization and dissolution of the citric acid in the PDMS for fabricating high uniform and small size pores. The present porous PDMS layer (i) decreases the pore size 93.2%p and increases the pore size uniformity 425%p compared to the conventional porous PDMS layer of mixing sugars and PDMS; (ii) is able to be fabricated in the thickness of 21-101 μm by spin-coating; (iii) has the 2.2 times higher water vapor transmission rate (947±10.8 g/day/m2) compared to the human skin water vapor transmission rate. The present porous PDMS layer reduces the skin trouble effectively by having the high water vapor permeability, therefore is applicable to the human daily-life skin attachable devices.


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 and high-throughput CTC isolation4)




Tapered slit filter for viable and high-throughput CTC isolation



A tapered slit filter (TSF) is developed for a high throughput isolation of viable and heterogeneous CTCs. The heterogeneous CTCs are isolated at the whole blood flow rate of 25 ml/hr, where the CTC capture efficiency of 87.4±5.8%, leukocyte removal rate of 99.7±0.4%, and the viability 88.3±8.1% are demonstrated experimentally. Compared with conventional EpCAM-targeting CTC isolation devices and size-based filters with straight-walled slits, TSF could capture tumor cells expressing low EpCAM at the cell surface and maintain high cell viability by reducing the stress on cells. The present filter facilitates precise diagnosis and further analysis of the patient, which can provide in-depth information about cancer recurrence and metastasis.


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.

Key Achievements

1. Minho Seok, Sunghyun Yoon, Mookyum Kim, and Young-Ho Cho*, “A Porous PDMS Pulsewave Sensor with Haircell Structures for Water Vapor Transmission Rate and Signal-to-Noise Ratio Enhancement,” Nanoscale Advances, Vol.3, Issue 16 (Aug. 21, 2021) pp.4843-4850.


2. Sunghyun Yoon, Minho Seok, Mookyum Kim, and Young-Ho Cho*, “Wearable Porous PDMS Layer of High Moisture Permeability for Skin Trouble Reduction,” Scientific Reports, Vol.11, Article No.938 (Jan. 13, 2021) pp.1-11.  


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. Jae-Eul Shim, Jiyoon Bu, Mi-Kyung Lee, Young-Ho Cho*, Tae-Ha Kim, Jong-Uk Bu and Sae-Won Han, “Viable and High-throughput Isolation of Heterogeneous Circulating Tumor Cells using Tapered-slit Filters,” Sensors and Actuators : B, Vol.B321, Article 128369 (Oct. 15, 2020) pp.1-8. 


5. Yoon-Tae Kang, Min-Ji Kim, 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.