Date of Award

Fall 12-14-2022

Degree Type


Degree Name

Master of Science (MS)



First Advisor

Dr. Gangli Wang

Second Advisor

Dr. Shahab Shamsi

Third Advisor

Dr. Xuefei Li


Negative differential resistance (NDR) is an electrical phenomenon in which current decreases with the increase in voltage magnitude, a non-ohmic behavior. NDR has been used extensively in producing amplifiers, oscillators, logic devices, transistors, and resistive switching devices. We experimentally describe how this phenomenon can be induced in the electrokinetic ion transport through a single conical nanopipette in simple ionic solutions (potassium chloride). The magnitude of the NDR effect is characterized to depend on the electrolyte concentration, ion enrichment voltage, time, cation mobility, and scan rate. The NDR magnitude intensifies with higher enrichment potential, longer enrichment duration, and slower potential scan rates. Our findings indicate that the NDR effect can be induced through the rectified ion transport hysteresis without external pressure, concentration gradient, and supporting electrolytes. The NDR properties further expand the scope of the nanopipette-confined ion transport as previously established novel memristor systems for aforementioned applications.


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