arXiv subjects

Burhan Ahmed

Publications and source records attributed to Burhan Ahmed.

3 recordsLinked to original sources

arXiv2026

Microscopy of Bioelectric Potentials using Electrochromism

Studying the electrical signals generated by living cells is key to understanding numerous biological phenomena. Electrochromic optical recording (ECORE) uses the electrochromism exhibited by certain materials to noninvasively measure these signals in real time. In this work, we report on the development of ECORE based on a high-NA microscope objective. We demonstrate the recording of extracellular action potentials from cardiomyocytes with single-cell resolution and a high sensitivity of 6.3 {\mu}V. Combining ECORE with microscopy simplifies the optical setup, allows for the simultaneous imaging of specimens, and makes ECORE accessible to a broader community of researchers, allowing for a better understanding of the biological processes that are integral to life.

physics.optics↗

arXiv2023

Compact Electrochromic Optical Recording of Bioelectric Potentials

Electrochromic optical recording (ECORE) is a label-free method that utilizes electrochromism to optically detect electrical signals in biological cells with a high signal-to-noise ratio and is suitable for long-term recording. However, ECORE usually requires a large and intricate optical setup, making it relatively difficult to transport and to study specimens on a large scale. Here, we present a compact ECORE apparatus that drastically reduces the spatial footprint and complexity of the ECORE setup whilst maintaining high sensitivity. An autobalancing differential photodetector automates common-mode noise rejection, removing the need for manually adjustable optics, and a compact laser module conserves space compared to a typical laser mount. The result is a simple, easy-to-use, and relatively low cost system that achieves a sensitivity of 16.7 μV (within a factor of 5 of the shot noise limit), and reliably detects action potentials from Human-induced pluripotent stem cell (HiPSC) derived cardiomyocytes. This setup can be further improved to within 1.5 dB of the shot noise limit by filtering out power-line interference.

physics.optics↗

arXiv2019

Interplay of Charge Density Wave States and Strain at the Surface of CeTe$_{2}$

We use scanning tunneling microscopy (STM) to study charge density wave (CDW) states in the rare-earth di-telluride, CeTe$_{2}$. In contrast to previous experimental and first-principles studies of the rare-earth di-tellurides, our STM measurements surprisingly detect a unidirectional CDW with $\textit{q}$ ~ 0.28 $\textit{a}$*, which is very close to what is found in experimental measurements of the related rare-earth tri-tellurides. Furthermore, in the vicinity of an extended sub-surface defect, we find spatially-separated as well as spatially-coexisting unidirectional CDWs at the surface of CeTe$_{2}$. We quantify the nanoscale strain and its variations induced by this defect, and establish a correlation between local lattice strain and the locally-established CDW states. Our measurements probe the fundamental properties of a weakly-bound two-dimensional Te-sheet, which experimental and theoretical work has previously established as the fundamental component driving much of the essential physics in both the rare-earth di- and tri-telluride compounds.

cond-mat.mtrl-sci↗