The interaction between biotin-streptavidin is one of the highest non-covalent affinities known with a Kd �� 10?14�C10?16 M [20,21] and was used for characterization of micro- and nanomechanical INCB028050 biosensors [3,22,23].2.?Experiment2.1. Design and Fabrication of the Lam�� Inhibitors,Modulators,Libraries Mode SensorThe details of the design procedure and characterization of the sensor can be found in [24,25]. The sensor structure consists of a thin square resonator supported by four anchors at the corners and surrounded by four drive/sense electrodes (Figure 1a). Inhibitors,Modulators,Libraries The square plate is separated from the surrounding electrodes with a 80 nm nitride gap that defines the capacitance of the electro-mechanical transducer. The resonator is laterally driven with electrodes on two opposite sides of the square plate symmetrically.

A DC-bias voltage (Vp) is applied to the structure via the anchors, while two AC input voltages are applied to the input electrodes with 180�� of phase difference. These voltages result in a time-varying electrostatic force on Inhibitors,Modulators,Libraries the plate edges which makes it oscillate Inhibitors,Modulators,Libraries in its fundamental frequencies in the Lam�� mode. The capacitive gap distances of the opposite side change with this same frequency. Because of the electrostatic field in the gap, a time-varying current is induced in the output electrode. A SEM micrograph of the square resonator, showing the resonator and its surrounding electrodes is depicted in Figure 1b.Figure 1.(a) Schematic of the device showing the resonator, exciting and sensing electrodes, driving and biasing setup (b) SEM microgrpagh of the fabricated mass sensor, silicon resonator, support beams and its surrounding polysilicon electrodes.

If the material of the square plate is homogeneous and isotropic, and if the side length of the square, L is much larger than its thickness, the square resonator can be theoretically modelled as a thin plate. In this case, the resonant frequency of Lam�� mode can be calculated as below Drug_discovery [18]:f0=n2LC44��(1)where n is the order of the resonance mode, �� is the material density and C44 is stiffness constant which is the shear modulus of the silicon G. For the single-crystal silicon structure, the material properties are as follows: �� = 2330 kg/m3 and G = 70 GPa. Replacing these values in Equation (1), the corresponding resonant frequency of a square resonator with L = 100 ��m will be f0 = 38.75 MHz.

Mass sensitivity of the biosensor is defined as the shift in the sensor resonance frequency due to the changes in the mass. A higher mass sensitivity helps to measure smaller masses. The mass sensitivity Sm of the selleck bio bulk-wave resonator mass sensor was defined by Sauerbrey as below [26]:Sm=12m=12��rt(2)The definition of the mass sensitivity depends on the density of the resonator structure material (��r) and resonator’s thickness (t) and is valid for the sensor vibrating in the air. The mass sensitivity of the sensor (Sm) in the air for the fabricated devices was analytically evaluated to be 107.