• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.1179-1182
• /
• 2005

To facilitate the cell based robot research, we presented a micro-mechanical force measurement system for the biological muscle actuators, which utilize glucose as a power source for potential application in a human body or blood vessels. The system is composed of a micro-manipulator, a force transducer with a glass probe, a signal processor, an inverted microscope and video recoding system. Using this measurement system, the contractile force and frequency of the cardiac myocytes were measured in real time and the magnitude of the contractile force of each cardiac myocyte on a different condition was compared. From the quantitative experimental results, we estimated that the force of cardiac myocytes is about $20{\sim}40\;{\mu}$N, and showed that there is difference between the control cells and the micro-patterned cells.

• Journal of Mechanical Science and Technology
• /
• 제20권5호
• /
• pp.668-674
• /
• 2006

In order to develop a cell based robot, we present a micro-mechanical force measurement system for the biological muscle actuators, which utilize glucose as a power source. The proposed measurement system is composed of a micro-manipulator, a force transducer with a glass probe, a signal processor, an inverted microscope and video recording system. Using this measurement system, the contractile force and frequency of the cardiac myocytes were measured in real time and the magnitudes of the contractile force of each cardiac myocyte under different conditions were compared. From the quantitative experimental results, we could estimate that the force of cardiac myocytes is about $20\sim40{\mu}N$, and show that there are differences between the control cells and the micro-patterned cells.

• Korean Chemical Engineering Research
• /
• 제47권5호
• /
• pp.538-545
• /
• 2009

본 총설에서는 주사형프로브현미경의 원리와 응용에 관하여 간략히 설명하고 최근 본 그룹에 의하여 활발하게 연구되고 있는 나노탐침과 AFM(원자간력현미경 atomic force microscopy)을 이용한 저침습성(low-invasive) 단일세포 조작기술과 고효율 유전자 도입기술을 소개하고자 한다. 시판 AFM 탐침을 침상구조로 가공한 나노탐침과 AFM을 이용하였을 경우, 탐침의 세포삽입의 성공여부를 force-distance curve 상의 척력소실의 유무로 판단할 수 있다. 침상 나노탐침을 사용하면 대부분의 세포에서 80~90%의 고효율 세포삽입이 가능하여 마이크로인젝션용 미세관을 이용하는 경우보다 세포삽입효율이 높았다. 또한 나노탐침의 직경이 400 nm 이하의 경우에는 세포 종류에 관계없이 장시간 나노탐침의 삽입에도 세포활성에 큰 영향이 없었다. 침상나노탐침을 이용하여 DNA를 도입하였을 경우에도 기존의 DNA 도입방법과 비교하여 높은 도입효율과 유전자 발현율로 DNA를 도입할 수 있는 가능성을 확인하였다.

• 한국기계가공학회지
• /
• 제13권6호
• /
• pp.30-36
• /
• 2014

Many different cells types have been found to be highly sensitive to mechanical force imposed by their surroundings. The cellular response to external mechanical forces has very important effects on numerous biological phenomena. In spite of its importance in biological processes, the cell adhesion force remains difficult to measure quantitatively at the cellular level. In this paper, to enhance quantitative measurements of cell adhesive interactions, a new attaching system and a method in which a glass bead can be attached to an AFM cantilever was designed and fabricated, and the degree of range displacement was controlled in the system. In an experiment, the movement of the stage in the attaching system and the attaching process were measured. The effectiveness of this system was confirmed as well in the experiment. In addition, through a commercial AFM system, the spring constant of the modified AFM probe could be measured.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.129.1-129.1
• /
• 2013

Atomically-thin graphene is the ideal model system for studying nanoscale friction due to its intrinsic two-dimensional anisotropy. Here, we report the reduced nanoscale friction of epitaxial graphene on SiC, investigated with conductive-probe atomic force microscopy/friction force microscopy in ultra-high vacuum. The measured friction on a buffer layer was found to be 1/8 of that on a monolayer of epitaxial graphene. Conductive probe atomic force microscopy revealed a lower conductance on the buffer layer, compared to monolayer graphene. We associate this difference in friction with the difference in total lateral stiffness. Because bending stiffness is associated with flexural phonons in two-dimensional systems, nanoscale frictional energy should primarily dissipate through damping with the softest phonons. We investigated the influence of hydrogen intercalation on the nanoscale friction. We found that the friction decreased significantly after hydrogen intercalation, which is related to loose contact between the graphene and the substrate that results in a lower bending stiffness.

• Tribology and Lubricants
• /
• 제33권3호
• /
• pp.92-97
• /
• 2017

The understanding of the friction characteristics of micro-textured surface is of great importance to enhance the tribological properties of nano- and micro-devices. We fabricate rectangular patterns with submicron-scale structures on a Si wafer surface with various pitches and heights by using a focused ion beam (FIB). In addition, we fabricate tilted rectangular patterns to identify the influence of the tilt angle ($45^{\circ}$ and $135^{\circ}$) on friction behaviour. We perform the friction test using lateral force microscopy (LFM) employing a colloidal probe. We fabricate the colloidal probe by attaching a $10{\pm}1-{\mu}m$-diameter borosilicate glass sphere to a tipless silicon cantilever by using a ultraviolet cure adhesive. The applied normal loads range between 200 nN and 1100 nN and the sliding speed was set to $12{\mu}m/s$. The test results show that the friction behavior varied depending on the pitch, height, and tilt angle of the microstructure. The friction forces were relatively lower for narrower and deeper pitches. The comparison of friction force between the sub-micro-structured surfaces and the original Si surface indicate an improvement of the friction property at a low load range. The current study provides a better understanding of the influence of pitch, height, and tilt angle of the microstructure on their tribological properties, enabling the design of sub-micro- and micro-structured Si surfaces to improve their mechanical durability.

• 전기화학회지
• /
• 제9권2호
• /
• pp.84-88
• /
• 2006

본 연구에서는 주사탐침현미경을 이용한 Si 표면의 국부 산화피막 형성에 있어서, 탐침이 움직이면서 생기는 $SiO_2$의 일차원적인 선의 높이가 탐침 전위, deflection setpoint, 탐침 속도에 의해 어떻게 영향을 받는지 고찰해 보았다. -3 V 보다 작은 탐침 전위에서는 국부 산화피막 형성이 관찰되지 않았으며 -3 V 보다 큰 탐침 전위에서는, 탐침 속도가 $1{\mu}m/s$일 때, 1 V씩 증가함에 따라 0.47nm의 비율로 선의 높이가 높아졌다. Deflection setpoint는 탐침이 가하는 기계적인 힘의 표지가 되는데, $12\sim18nN$ 정도의 힘이 가해지지 않으면 국부 산화피막 형성이 관찰되지 않았다. 그 이상의 힘이 가해져야 국부 산화피막 형성이 관찰되는데 이때 선의 높이는 기계적인 힘과 무관하였다. 탐침 속도가 빨라짐에 따라 선의 높이는 낮아졌으나, 탐침 전위가 -5V인 경우, 0.7nm 이하로 낮아지지는 않았다.

• Tribology and Lubricants
• /
• 제35권3호
• /
• pp.169-175
• /
• 2019

In lithium-ion batteries (LIBs), the stress induced by the volume change of an electrode during charge-discharge processes may often cause the mechanical integrity of the electrode to degrade. Polymer binders with enhanced mechanical properties are preferred for improved mechanical integrity and cycling stability of the electrode. In addition, given that sliding and shearing between the polymer binder and components in the electrode may readily occur, frictional and adhesion characteristics of the polymer binder may play a critical role in the mechanical integrity of the electrode. In this study, frictional and adhesion characteristics of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) were investigated using a colloidal probe atomic force microscope. Friction loops were obtained under various normal forces ranging from 0 to 159 nN in air and electrolyte and then the interfacial shear strengths of PAN and PVDF in air were calculated to be $1.4{\pm}0.5$ and $1.3{\pm}0.3MPa$, respectively. The results show that in electrolyte, interfacial shear strength of PAN decreased slightly ($1.2{\pm}0.2MPa$), whereas that of PVDF decreased drastically ($0.06{\pm}0.01MPa$). Decreases in mechanical properties and adhesion in electrolyte may be responsible for the decrease in interfacial shear strength in electrolyte. The findings from this study may be helpful in developing polymer binders to improve the mechanical integrity of electrodes in LIBs.

• 전기학회논문지
• /
• 제59권1호
• /
• pp.82-87
• /
• 2010

A measurement system of contact force between overhead contact line and pantograph of train is developed which measures the contact force by using four sets of full-bridge strain gauges instead of load cells and accelerometers. The sensors are installed on the pan head of pantograph and the measured data from the sensors are transmitted to a server system in the train by way of wireless Lan. This configuration of the measuring system makes it easy to install on the trains without any alteration of train system. The measurement system is applied to KTX on the Kyungbu high speed line, and the measured contact force data shows good agreement with those measured by load cell and accelerometers. The waveform of the contact force between overhead contact line and pantograph contains essential information about their conditions. The proposed measurement system can probe any defects on overhead contact lines with train running at high speed, which will be a powerful solution for the maintenance of long-distance overhead contact lines.

• ETRI Journal
• /
• 제32권5호
• /
• pp.722-728
• /
• 2010

This paper presents the design and fabrication model of a touchpad based on a contact-resistance-type force sensor. The touchpad works as a touch input device, which can sense contact location and contact force simultaneously. The touchpad is 40 mm wide and 40 mm long. The touchpad is fabricated by using a simple screen printing technique. The contact location is evaluated by the calibration setup, which has a load cell and three-axis stages. The location error is approximately 4 mm with respect to x-axis and y-axis directions. The force response of the fabricated touchpad is obtained at three points by loading and unloading of the probe. The touchpad can detect loads from 0 N to 2 N. The touchpad shows a hysteresis error rate of about 11% and uniformity error rate of about 3%.