Jungchul Lee

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Using suspended nanochannel resonators (SNRs), we demonstrate measurements of mass in solution with a resolution of 27 ag in a 1 kHz bandwidth, which represents a 100-fold improvement over existing suspended microchannel resonators and, to our knowledge, is the most precise mass measurement in liquid today. The SNR consists of a cantilever that is 50 microm(More)
An intrinsic uncertainty in particle mass sensing with the suspended microchannel resonator results from variation in a particle's position near the free end of the resonator. To circumvent this error we employ the second flexural bending mode. This mode exhibits additional frequency peaks while particles pass over the antinode, a point where the frequency(More)
Energy dissipation experienced by vibrating microcantilever beams immersed in fluid is strongly dependent on the mode of vibration, with quality factors typically increasing with mode number. Recently, we examined energy dissipation in a new class of cantilever device that embeds a microfluidic channel in its interior – the fundamental mode of vibration(More)
Nanomechanical resonators can quantify individual particles down to a single atom; however the applications are limited due to their degraded performance in solution. Suspended microand nanochannel resonators can achieve vacuum level performances for samples in solution since the target analyte flows through an integrated channel within the resonator. Here(More)
This paper presents the design and application of microcantilever heaters for biochemical applications. Thermal lysis of biological cells was demonstrated as a specific example. The microcantilever heaters, fabricated from selectively doped single crystal silicon, provide local resistive heating with highly uniform temperature distribution across the(More)
This study aimed to find the effects of 12-week chiropractic and lumbar exercise program on the lumbar muscle strength and Cobb's angle in 16 adolescent students with scoliosis. The patients with scoliosis did not have neurological symptoms and surgery experience. Each group of eight subjects received chiropractic and lumbar exercises three times a week.(More)
This paper investigates the electrical and thermal response of the heated atomic force microscope (AFM) cantilevers in the frequency range from 10 Hz to 1 MHz. Spectrum analysis of the cantilever voltage response to periodic heating distinguishes different thermal behaviors of the cantilever in the frequency domain: the cantilever voltage at low frequencies(More)
This article describes tapping mode atomic force microscopy (AFM) using a heated AFM cantilever. The electrical and thermal responses of the cantilever were investigated while the cantilever oscillated in free space or was in intermittent contact with a surface. The cantilever oscillates at its mechanical resonant frequency, 70.36 kHz, which is much faster(More)
Physical characterization of nanoparticles is required for a wide range of applications. Nanomechanical resonators can quantify the mass of individual particles with detection limits down to a single atom in vacuum. However, applications are limited because performance is severely degraded in solution. Suspended micro- and nanochannel resonators have opened(More)
Microscale engineering technologies derived from the semiconductor and microelectronics industries provide new opportunities in biology to create and precisely control threedimensional cell culture microenvironments in a physiologically relevant and organ-specific context. Here we review recent advances in the development of ‘Organs-on-Chips’ in which(More)