Action potentials of electrogenic cells, such as neurons and cardiomyocytes, are crucial for their physiological functions. To record action potentials, an ideal electrophysiological technique shall be able to detect action potentials from individual cells and measure the shape of intracellular action potential. However, the current electrophysiological methods, intracellular and extracellular recording, suffer severe limitations. Intracellular recording technique such as patch clamp are invasive and laborious, constraining the throughput to recording only one cell at a time. Extracellular recording such as planar electrode array cannot detect fine features of action potentials and lacks one-to-one cell to electrode correspondence. Worked with Prof. Bianxiao Cui at Stanford and Prof. Zeinab Jahed at UCSD, we developed nanoscale, minimally invasive, solid-state electrical probes to achieve parallel intracellular recording. Nanoscale electrode probes have shown the promise of fundamentally overcome the limitations of current electrophysiology techniques. However, the recorded signals using similar nanoelectrodes often show large variations. From electrical modeling of the cell-electrode interface, we identify two primary factors that would affect the signal amplitude and the signal variations – the membrane-to electrode sealing resistance and the membrane access resistance. We employed advanced nanofabrication methods to engineer a new generation of electrophysiology tools. Nanotechnology allows us to design the 3-dimensional geometry of nanoelectrodes to achieve tight coupling between the cell membrane and the electrode, which will not only simplify signal source attribution but also significantly improve the signal-to-noise ratio relative to planar recording systems.