## 1 Introduction
As was noted by the authors [27], their results are in contradiction with commonly accepted assumptions (which state the electrization of the drop is caused not by pre-developed charges on the pipette, but by the distribution of charges between the drop and the pipette tip surface). Such a triboelectric effect, described above, occurring upon the injection of a liquid with pipette tips, should also take place in nanotechnological highly sensitive atomic force microscopy (AFM)-based and nanowire biosensors, which are promising for the early diagnosis of diseases. In such biosensors, when an electric charge is generated in the supply system, it is supposed to play an important positive role in providing highly sensitive protein detection [2; 28]. So, in [28], we demonstrated that a correlation is observed between the amount of protein, captured onto the sensor chip in the system for AFM-based fishing, and the charge generated per single protein particle. In a number of papers, the negative effects of charge jumps--which occur upon the injection of solutions into a highly sensitive biosensor (for instance, into a nanowire-based one)--were demonstrated. Negative effects can lead to a significant change in the baseline signal during measurements [29; 30]. Such charge jumps can even cause a failure in nanowire biosensors, particularly if the nanowire thickness is very low (of the order of 100 nm). Previously, we demonstrated [30; 31; 32] that at a temperature of between 35 \({}^{\circ}\)C and 38 \({}^{\circ}\)C and a continuous supply of either water or highly diluted (femtomolar) protein solutions with a low (0.9 mL/min) flow rate, a stepwise accumulation of charge in the measuring cell of such biosensors can be observed. At this point, the appearance and magnitude of the charge jumps depends on the distance between the tip nozzle of the supply system and the grounded electrode [31]. In the present study, we report the results of the continuation of our research on the appearance of charge jumps upon the injection of solutions obtained not at a fixed flow rate, but at varying the flow rate over a broad range. The dependence of the amount of charge--generated in such an analyte supply system--on the liquid flow rate has been determined. In the experiments, the specially made highly sensitive measurement system based on an electrometer is also employed. The measurements have been carried out at a temperature of 38 \({}^{\circ}\)C, which is often used in biosensor measurements and corresponds to a pathological state of a human body. It has been demonstrated that upon supplying water with varying its flow rate over a broad range (from 0.9 to 7.2 mL/min), a linear-stepwise accumulation of charge in the measuring cell can be observed. It has been found that, upon transition from the drop-by-drop mode of water injection to the jet flow, with increasing the supply flow rate, the amount of charge accumulated in the measuring cell also increases. At that point, the magnitude of the jumps in the time dependence of charge accumulation does not depend on the supply flow rate. The results obtained herein should be taken into account in the development of highly sensitive protein detection systems, including those for AFM-based fishing and nanowire detectors. Highly sensitive protein detection systems are in high demand in the field of early medical diagnosis of diseases such as brain cancer, prostate cancer and other aggressive oncological pathologies. The results obtained herein can also be used in the development of refined models of hemodynamics.