A nano-radar for cell imaging: 3D microwave microscopy and fluorescence in a liquid medium

The electrical activity of cellular organelles such as mitochondria plays a key role in biology and medicine, but remains poorly understood. Its link with aging, apoptosis and diseases such as cancer and diabetes raises essential questions. Developing a calibrated, broadband electronic interface would enable to explore these phenomena and pave the way for new therapeutic approaches.

 Early work

In 2017, a consortium comprising the IEMN, the University of California Irvine, the Center for Mitochondrial and Epigenomic Medicine at the Children’s Hospital of Philadelphia, USA, carried out the first-ever imaging of living mitochondria using scanning microwave microscopy. Mitochondria, isolated from cultured HeLa cells, are attached to a graphene support and kept alive by a respiratory buffer that supplies them with the nutrients required for the Krebs cycle. The organelles are analyzed by capacitive measurement at a frequency of 7 GHz.

 A nanoelectronic broadband interface inside living cells with integrated fluorescence readout of metabolic activity.

In 2020, the consortium achieves a major breakthrough by presenting the very first calibrated broadband electrical connection inside a living cell with integrated fluorescence readout of metabolic activity. On-chip, nanoscale capacitance calibration standards are used to quantify microwave response with cellular images obtained at 22 GHz. Such an interface opens up numerous prospects for the integration of life sciences with nanoelectronics, notably for electronic testing of membrane potential dynamics, nanoelectronic activation of cellular processes, as well as nano-radar tomographic imaging of the morphology of vital organelles within the cytoplasm, throughout the cell life cycle, in different physiological environments and under various pharmacological conditions.