The sensitivity of a biosensor is always the first and one of the most important parameters when judging its performance. For example, the detection of one specific antibody in a human blood sample would suppress the effects of all other antibodies, cells, electrolytes, etc.
Future research interests
Conclusions
Highly sensitive multipoint real-time kinetic detection of surface plasmon bioanalytes with custom CMOS cameras. Gold Nanoparticle Functionalized Surface Plasmon Resonance Optical Fiber Biosensor: In Situ Detection Of Thrombin With 1 n.M Detection Limit.
Introduction
The nanofluid convective heat transfer mechanism in the micro-grinding zone is investigated, and the heat transfer enhancement mechanism of solid nanoparticles and the heat distribution mechanism in the micro-grinding zone are revealed. In current neurosurgery, surgeons commonly perform drip irrigation with normal saline (NS) in the grinding zone according to the following principle: The heat is dissipated by convective heat transfer to cool the surgical area. In recent years, studies have initially investigated the problem of thermal injury existing in the bio-bone grinding process.
Taking the heat transfer problem and its inverse problem in the bone grinding process with a miniature spherical grinding tool, Zhang et al. For the bottleneck problem in current clinical neurosurgical bone surgery, namely irreversible thermal damage, an NJMC bio-bone microgrinding process was put forward.
Grinding temperature field
The solution method of grinding temperature field
Therefore, the basis for the superposition method of heat source temperature fields is the resolution of this temperature field at any time after transient point heat sources in an infinite object immediately emit a partial amount of heat. The finite element method based on the numerical method is another effective method for calculating the grinding temperature field between the analytical method and the finite element method. There are few reports on the calculation of the grinding temperature field through the finite difference method, so this method will be described in detail here.
Temperature field of biological bone micromilling under nanoparticle mist cooling: http://dx.doi.org/10.5772/intechopen.91031. Temperature field of biological bone micromilling under nanoparticle mist cooling: http://dx.doi.org/10.5772/intechopen.91031.
Boundary condition
A boundary condition of this type is a forced convective boundary condition, namely the temperature value at the boundary of a given object at any moment, also called the Dirichlet condition:. where Twi is the set temperature at the boundary surface sf. A boundary condition of this type refers to the heat flux at the boundary surface of the object in the normal direction at any time and is also called the Neumann condition. The relationship between the temperature gradient and the heat flow is obtained by Fourier's law and is equivalent to the rate of change of temperature at the boundaries in the normal direction at any time: where Q is the amount of heat passing through the boundary surface sf. Qw = 0 when the boundary is below the thermal insulation. Q is a fixed value when the thermal conductivity at the boundary is constant and is a function related to time when the thermal conductivity varies with time.
Boundary condition of this type indicates convective heat transfer between boundary surface and surrounding medium, and it is also called Robin condition. It can be known from Newton's law of cooling that convective heat transfer takes place between boundary layer of the sample and cooling heat transfer medium:. true convective heat flux at the boundary surface between cooling heat transfer medium and sample and its convective heat transfer coefficient at the boundary between cooling heat transfer medium and sample.
Heat distribution coefficients
Experimental study on micro grinding of biological bone with nanoparticle jet mist cooling
Nanoparticle jet mist cooling bone micro grinding experimental platform Figure 5 shows the established experimental platform of NJMC bio-bone micro
Thermocouple clamping mode: a blind hole drilled on the back of the bone sample has a certain distance from the bone surface (grinding depth), the thermocouple wire is placed in the blind hole, the bone sample is fixed on the dynamometer, and the force and temperature of the microbone grinding process are measured simultaneously. In the biomedical field, HA, SiO2 and Al2O3 nanoparticles have non-toxicity and good biological compatibility and are commonly used drug carriers in nanodrug release system [33, 34]; NS is a commonly used clinically used cooling medium, as the osmotic pressure is basically equal to the osmotic pressure of human plasma. Therefore, HA, SiO2, and Al2O3 nanoparticles with a diameter of 50 nm were used as nanoscale solid additives and NS as a nanofluid base to prepare HA, SiO2, and Al2O3 nanofluids.
When using a dispersing agent with a volume fraction of 2 vol.% and 2 vol.%, the stability of the nanofluid suspension will be the best. Therefore, the nanofluid preparation method in this chapter was the “two-step method”, namely, adding 2 mL of HA, SiO2, and Al2O3 nanoparticles and 0.2 mL of PE into 100 mL of NS, supplemented with ultrasonic vibration for 15 minutes.
Temperature field of bio-bone micro grinding with different cooling methods
Temperature field in the cut-in, steady-state and cut-out zones during bone microgrinding. The temperature in the grinding zone is low because the volume of material involved in grinding in the cut zone is small with low energy consumption. However, in the temperature field of bone micro-grinding with a loaded dynamic heat flow, as shown in the figure, the temperature value changes continuously after the equilibrium state is reached [38, 39].
Cutting zone: As shown in Figures 9(d) and 10, according to the heat transfer theory, undeformed thickness is gradually reduced when the grinding tool is in the cutting zone, and the volume of sample material participating in. If the amount of heat generated at the grinding interface remains unchanged, the volume of the material to which heat is migrated in the cutting zone is reduced.
Effect of nanoparticle size on bone micro grinding temperature
2.Steady-state zone: In Figures 9(b), (c) and 10, the undeformed section thickness is maintained at the average value, and the surface temperature no longer continues to rise, namely, the formed temperature field reaches a steady state. As for the grinding temperature fields previously calculated by researchers, after a constant heat flux is charged, the temperature value below which a steady state is reached will not be changed. Mist cooling was taken for comparative experiment and for measurement of grinding force and temperature at measurement point T2.
Conclusions
A study on the thermal characteristics of a micro-scale grinding process using minimal nanofluid (MQL) lubrication. Grinding Mechanics Analysis and Improved Predictive Force Model Based on Material Removal and Plastic Stacking Mechanisms. However, the combined effect of material removal and plastic stacking on the grinding force model has not been investigated.
An improved theoretical force model that takes into account material removal and plastic stacking mechanisms was presented. With the need for green manufacturing, nanofluid minimum quantity lubrication (NMQL) was introduced for grinding [1, 2], which could effectively improve cooling and lubrication performance compared to conventional dry or flooded conditions [3, 4].
Material removal mechanism of NMQL grinding 1 Deformation and strain rate
Mechanism of chip formation .1 Theoretical research
Adiabatic shear effect refers to constitutive instability (thermal viscoplastic instability) of the material under impact load. Extreme strain exists in the shear zone of the material removal under impact loading, and the shear zone is a thermally insulating environment within a very short time. As shown in Figure 5(b), under a high stress rate, assume that the shear zone of grinding chips is in an isothermal environment: the material deformation stress in the stress hardening stage is much higher than that under quasi-static conditions, and this phenomenon is called "strain strengthening effect" of plastic deformation of material, and the deformation resistance is improved under stress strengthening effect.
As shown in Figure 5(c), taking into account the temperature rise at the abrasive particles/grindings interface at high strain rate, the plastic deformation process of the material at this time is an extensive result of the strain hardening effect and the thermal softening effect, namely the adiabatic shear process. As the strain rate increases, the heat transferred to the shear region also increases, the effect of thermal softening becomes more obvious, and the material rupture limit ratio under the three boundary conditions is σb2>σb3>σb1.
Mechanism of furrow formation and cutting efficiency .1 Plastic stacking effect
Otherwise, the area of the shear slip layer obtained under dry grinding conditions is small, that in the MQL condition is larger and that under the NMQL is the largest, where rupture also occurs. On the one hand, as the lubrication effect increases and the friction coefficient decreases continuously in the three lubrication conditions, the strain rate in the primary deformation zone at the same rate increases successively, so does the shear slip distance in the three conditions. Therefore, the effect of thermal softening during the chip forming process of NMQL cutting is lower than that in dry grinding condition.
Shear layer slippage of grinding chips is mainly material fracture, followed by plastic flow, so the distance between the shear layers is greater, and the grinding chips even break. Belt chips are still formed due to thermal softening effect in dry grinding, chip breakage caused by excessive shear layer spacing also occurs under MQL condition, and the breakage under NMQL condition is further aggravated.
Force model of single grain 1 Stress state of grain
- Force model in chip formation region ( α 1 – π /2)
- Force model in elastic-plastic flow region (0– α 1 )
- Force model of cutting and ploughing grain
- Frictional force model
The behavior of the material in the plowing phase can be categorized as plastic flow, in which the strain must reach δs. The magnitude of the force is determined by the stress and lubrication condition between the grains and the workpiece.
Grinding force model and prediction
- Procedure of modeling common grinding wheel
- Dynamic active grains in grinding zone
- Grinding force model
- Experimental verification
Concrete calculation of grinding power can be described in Figure 13; the grinding force can be expressed in Eq. For the nth cutting grains (1≤n≤Nc), agnis the depth of cut; Ftc(agn)/Fnc(agn) is the tangential/normal cutting force, respectively; andFtcf(agn)/Fncf(agn) are the tangential/normal friction force on the rake face of the cutting grain, respectively. Ftp(agm)/Fnp(agm) are the tangential/normal, respectively; andFtpf(agm)/Fnpf(agm) are the tangential/normal friction force on the rake face of plow grain, respectively.
The average percentage of deviation in the normal force is 4.19%, while that in the tangential force is 4.31%. For a certain grinding condition (dry grinding, Vs= 20 m/s, Vw= 2 m/min, ap= 15μm), the contribution of the tangential friction force in the total tangential grinding force is approx. 89.17% and approx. 90.71% for normal power.
Conclusions
Surface morphology evaluation of multi-angle 2D ultrasonic vibration integrated with nanofluid minimum amount lubrication grinding. Experimental evaluation of MoS2 nanoparticles in jet MQL milling with different types of vegetable oil as base oil. Predictive model for minimum chip thickness and size effect in single diamond grain grinding of zirconium ceramics under different lubrication conditions.
Predictive modeling of grinding force considering wheel deformation for toric less axial grinding of large complex optical mirrors. Experimental evaluation of cooling capacity with coefficient of friction and specific energy of friction in grinding lubrication with minimal amount of nanofluid with different types of vegetable oil.
