Encoding Electron Paramagnetic Resonance Signals as Phase Shifts

At the International Solid-State Circuits Conference (ISSCC) 2026, which took place in San Francisco, California, a team of researchers from CEA-Leti and CEA-IRIG-SyMMES presented their newly developed battery-operated electron paramagnetic resonance (EPR) spectrometer that is small enough to fit on a single microchip.^1,2 The results indicated how the device could be helpful in laboratory analysis.^1,2

One of the key attributes to this EPR-on-a-chip spectrometer is that it can encode EPR signals as phase shifts rather than amplitude or frequency changes. In this video clip, Jean-Baptiste David, who is a R&D Engineer at CEA-Leti, and Serge Gambarelli, who is a research director at CEA-IRIG and EPR spectroscopy expert, explains how this fundamentally change signal detection and noise performance in EPR spectroscopy.

The discussion focused on the development of an EPR on a chip spectrometer, highlighting the advantages of using an injection-locked oscillator (ILO) over a voltage-controlled oscillator (VCO) with a phase lock loop (PLL). The ILO allows for faster frequency scans, enabling spectra to be acquired in 200 nanoseconds, significantly faster than conventional EPR methods. This rapid scan speed is crucial for monitoring fast kinetic phenomena. The phase detection method reduces noise and increases signal-to-noise ratio by averaging multiple records, even for short-lived transients.

This clip was the third part of a five-part interview with Baptiste-David and Gambarelli. Part 1 of our video focused on the device and why it can benefit laboratory analysis.³ Baptiste-David and Gambarelli explained that unlike traditional laboratory versions that require massive magnets and high power consumption, this new device is battery-operated and highly portable. The system utilizes an integrated circuit and a unique signal detection method to achieve rapid scans without losing sensitivity or spectral range. This breakthrough enables on-site chemical analysis for industrial, medical, and environmental applications that were previously restricted to stationary labs. By transforming a bulky instrument into a handheld sensor, the technology allows for the real-time monitoring of reactive chemical species in the field. Part 2, meanwhile, concentrates on the application areas where EPR spectrometers could be useful.⁴

References

1. IEEE International Solid-States Circuit Conference, 2026 IEEE International Solid-States Circuit Conference. ISSCC.org. Available at: https://www.isscc.org/ (accessed 2026-04-06).
2. CEA-Leti, CEA-Leti Validates First Ultra-Fast, Battery-Operated EPR Spectrometer at Chip Scale. CEA-Leti. Available at: https://www.leti-cea.com/cea-tech/leti/english/Pages/What's-On/Press%20release/CEA-Leti-Validates-First-Ultra-Fast-Battery-Operated-EPR-Spectrometer-at-Chip-Scale.aspx (accessed 2026-04-06).
3. David, J.-B.; Gambarelli, S.; Wetzel, W. The Utility of Electron Paramagnetic Resonance Spectrometers in Laboratory Analysis. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/the-utility-of-electron-paramagnetic-resonance-spectrometers-in-laboratory-analysis (accessed 2026-04-16).
4. David, J.-B.; Gambarelli, S.; Wetzel, W. What Applications Benefit from EPR-on-a-Chip Devices? Spectroscopy. Available at: https://www.spectroscopyonline.com/view/what-applications-benefit-from-epr-on-a-chip-devices- (accessed 2026-04-16).