The gold layer is employed to prevent the corrosion of the cantil

The gold layer is employed to prevent the corrosion of the cantilever and to promote the immobilization of the bio-recognition element. Prior to the gold deposition, a thin layer of chromium with a thickness about 100 nm was sputtered on the cantilever as the adhesion layer.2.2. Operation principleIt thorough is known that the nth-mode bending resonance frequency of an undamped cantilever with one end rigidly clamped Inhibitors,Modulators,Libraries can be expressed as [23]:fn=��n22��12tL2E��(1-v2)(n=0,1,2,��.)(1)where the ��n2 (��0=1.875) is the dimensionless nth-mode eigenvalue, t and L are the thickness and length of the cantilever, while E, ��, and �� are the effective Young’s modulus, density, and the Poisson’s ratio of the beam material.

If a mass load (��m), which is much smaller than the mass (m) of the cantilever, is uniformly distributed on the surface of the cantilever, the change in the fundamental Inhibitors,Modulators,Libraries resonance frequency (f0) is ��f=-f0��m2m [15].Therefore, the corresponding Sm of the cantilever isSm,uni=-��f��m=f02m=��022��1212WL3E��3(1-v2)(2)where W is the width of the cantilever beam. If the ��m is at the tip Inhibitors,Modulators,Libraries of the cantilever, the Sm would be [15]Sm,tip=-��f��m=f00.472m=��022��1210.472WL3E��3(1-v2)(3)That is, the Sm of a cantilever depends on three factors: 1) the geometry of the cantilever (L and W), 2) the beam material (s)-E��3(1-v2), and 3) the location of the mass load.The length of the active layer in an MSMC would be changed with a magnetic field due to the magnetostrictive effect. Therefore, an applied magnetic field on an MSMC would lead to a length difference between the active and inactive layers, which would bend the MSMC since the active and inactive layers are bonded together.

Therefore, a time-varying magnetic field would make an MSMC bending vibration as shown in Figure 1(b). Due to the magnetic nature of the magnetostrictive alloy, the bending vibration of an MSMC would emit a magnetic signal, which can be measured using a pick-up coil (see Figure 1(c)).Figure Inhibitors,Modulators,Libraries 1.Schematic illustration of the principle of MSMC as a transducer for biosensors.If the time-varying magnetic field is a sine wave, the bending vibration of an MSMC would also be a sine function of time. The amplitude of the bending vibration of an MSMC changes with the amplitude and frequency of the magnetic field. Additionally, there would be a phase difference between the driving magnetic field and the bending vibration.

If an ac magnetic field is swept over a frequency range with a constant amplitude, as shown in Figure 1(a), the amplitude Anacetrapib of the bending vibration of the MSMC would change with the frequency as shown in Figure 1(d). The phase difference between the first magnetic field and the MSMC’s bending vibration also changes with resonant frequency as shown in Figure 2 and discussed below.Figure 2.The frequency dependence of the phase and amplitude signals from the lock-in amplifier for an MSMC in size of 2.8 mm (L) �� 1.

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