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[생명공학과 미래사회] 생명공학의 발달과 의학의 변화 -의학에서 활용될 생명공학 기술의 재조명과 전망에 대해
[생명공학] 생명공학의 정의, 중요성과 생명공학기술의 동향, 외국의 생명공학 육성 동향 및 생명공학의 문제점 그리고 향후 생명공학의 전망, 과제 분석
[생명공학] 소비생활과 관련된 생명공학 기술의 발전과 활용
Bio MEMS
[바이오산업] 바이오산업의 정의, 특징, 발전과 미국, 국내 바이오산업의 현황 및 바이오산업의 미국시장 진입전략 그리고 향후 바이오산업정책의 추진 과제 분석
미국의 바이오텍 바이오클러스터 산업분석
[공학기술] 나노기술과 의공학
[화학공학] 바이오센서(Biosensor) 기본개념 및 응용분야 조사
[생명공학]생명공학의 원리,발전, 생명공학의 핵심기술, 생명공학의 장점,단점, 생명공학의 현황, 향후 생명공학의 정책 방안 분석
[바이오센서] 바이오센서의 개념, 구성, 원리와 바이오센서의 현황 및 바이오센서의 이용 사례 분석
소개글
[의학공학] 바이오센서를 이용한 혈당량 측정에 관한 기술(영문)에 대한 자료입니다.
목차
-Abstract
-Keywords
-Introduction
-Cantilever detection Modes of operation
-Cantilever detection Modes of detection
-Glucose and pH Sensing in Exhaled Breath Condensate
-Conclusions
-REFERENCES
본문내용
Working in the static mode, the bending arises as a consequence of a surface stress change induced by any molecular reaction which takes places on only one of the cantilever surfaces. The induced surface stress change could be positive or negative, depending on the surface deformation generated. The factors and phenomena responsible for this change is today not fully understood due to the complex equilibrium between the sensing layer, and the surrounding water molecules, the bulk solution, the target molecules, ions, etc. Interactions coming from electrostatic, hydration, steric and van der Waals forces, changes in the surface hydrophobicity or conformational changes of the adsorbed molecules play an important role in the final bending.[1],[2] The easiest and most extended model to study the surface stress produced on cantilevers is based on the work of G.G Stoney in 1909. Looking for higher accuracy, some works have presented modifications on this model, depending on the thickness or roughness of the surface.[3] Other energy-based models studied the dependence of the cantilever bending with the density of the adsorbed atoms/molecules and the properties of the substrate.[4] Stoney’ model relates the total surface stress change between the top and the bottom sides (Ds1 Ds2) with the cantilever free end displacement, Dz, the Young’ modulus, E, the Poisson coefficient, n, and the cantilever length, L, and thickness, t, by,
For sensing biomolecular interactions in the static mode, only one surface of the microcantilever must be previously biofunctionalized and this can be a complex task especially when arrays of microcantilevers are employed.
In contrast to the static case, the dynamic mode does not require the functionalization of only one cantilever surface, as the cantilever resonance frequency change depends on the total mass adsorbed on both sides. In this mode, the microcantilever is used as a microbalance and extremely high sensitivities can be obtained (in the attogram regime), overcoming other similar and well-known mass detectors, such as the quartz crystal microbalance (QCM).[5] In first approximation cantilevers behave like a harmonic oscillator, and the mass change on a rectangular cantilever will produce a reduction on the resonance frequency, which can be estimated from:
where f0 and f1 are the fundamental resonance frequency before and after the mass adding, respectively.
Recent studies have demonstrated that surface stress can induce a microcantilever stiffness change, due to strain-dependent surface stress (elasticity), which can cancel or make negligible the resonance frequency change due to the added mass.[6–8] The induced cantilever stiffness change can produce a resonance frequency shift as high as the added mass, but increasing the microcantilever resonance frequency, depending on the attached protein density and thickness and the cantilever length.[9] Actually, this is one of the questions to be solved in order to avoid errors in the characterization of biological agents, being necessary to identify and detach the frequency shifts coming from the added mass and the stiffness changes.[10]
When working in the dynamic mode, the resolution of the system, Df, is determined by the quality factor, Q, following the expression △f=f/Q. The quality factor quantifies the energy dissipation and is defined as the ratio between the mechanical energy accumulated and dissipated per vibration cycle. Under liquids environments, the quality factor shifts toward much lower values than in air, due to the damping effect of the viscous surroundings, which decrease abruptly the overall sensitivity. For that reason, this way of operation is more difficult to implement and, until recently, most of the cantilever biosensors were based on the static mode.
Cantilever detection Modes of detection
In the optical lever scheme, the cantilever free end movement is detected by measuring the reflected laser beam displacement into a position-sensitive photodetector (PSD).