# Modeling of Integrated Nanoneedle-Microfluidic System for Single Cell Temperature Measurement
## 3 Results and Discussion
The graph showed that as the forces gradually increased, the displacement increased, and would overshoot when the force approximately reached 12 uN. This could be explained that the nanoneedle started to undergo permanent deformation and the bonds between the molecules weakened, which will need to be calibrated to perform successful measurements. Figure 12a shows the results of the nanoneedle damage. The maximum force that can be applied to the nanoneedle was 22.5 uN. This is sufficient for the purpose of cell penetration in particular yeast cell, as it has been proven that a force of up to 1 uN was needed for yeast cell penetration [23]. The plot of the strain energy versus the force applied in Figure 12b further confirmed the force at which the damage occurred since the strain drastically dropped when the force reached 22.5 uN. The third stage was the electrical measurement on _S. cerevisiae_ cell. Figure 13a,b show the simulation results of the voltage and the current density obtained from the _S. cerevisiae_ cell electrical measurement. Figure 10: Simulation results of the thermal electric characterization. (**a**) Current density at 293.15 K and (**b**) 333.15 K.  
As shown, the voltage clearly passed through the cell, which means that the voltage drop direction passed through the cell, confirming that the current had a path through the cell. From the current density shown in Figure 13b, the current density value was not different than the value obtained in Figure 10, which was done independent of the cell. This confirms that the cell conductivity had no  
Figure 11: Simulation result showing the pressure on the nanoneedle because of applying external forces. (**a**) The graph shows the location that had the effect under pressure; (**b**) Displacement of the nanoneedle as the force increased, the graph overshoot at 12 \(\upmu\)N.  
Figure 12: Simulation results of the mechanical characterization, which shows the damage on the nanoneedle. (**a**) The failure caused by the external forces when exceeding 22.5 \(\upmu\)N; (**b**) The strain energy of the nanoneedle; it drastically dropped when the force exceeded 22.5 \(\upmu\)N.  
Figure 13: Simulation results of the single cell electrical measurement. (**a**) The voltage drop across the cell results; (**b**) The current density results. effect on the nanoneedle conductivity. This also could be validated by comparing it to the current measurement of yeast cell obtained in [23] that was only in 262 pA. To further understand the analysis, a cross-sectional view was taken and presented in Figure 14a,b. From the results, the color legend clearly showed that the current passed through the nanoneedle and was absolutely independent of the cell conductivity. In addition, the direction the current took to reach the ground shown in Figure 14b was only within the nanoneedle. This further confirms that the measurement of the temperature is independent of the cell and it is only dependent on the nanoneedle conductivity characteristic and its intrinsic properties that change with the temperature. The second analysis was done to determine the temperature detection abilities of the nanoneedle. A plot of the current change as a function of temperature ranging from 293.15-333.15 K is shown in Figure 15. The behavior of the graph showed the same behavior as an RTD with a positive TCR: a decrease in the current as the temperature increased, which has an inverse relation to the resistance. The results confirmed that the nanoneedle was able to detect the temperature in the required range with a sensitivity of 0.015 \({}^{\circ}\)C having a difference of approximately 50 nA between the minimum and the maximum temperature. Another study was to examine how fast the nanoneedle responded to temperature change in the surrounding.