A Miniaturized Chip-based ODNP Platform

In this paper, we present a miniaturized chip-based Overhauser dynamic nuclear polarization (ODNP) platform for enhancing detection sensitivity and, thereby, improving the achievable limit of detection. The presented system uses three custom-designed ASICs for the excitation and the detection of the NMR signal as well as the generation and preamplification of the required microwave (MW) signal. A commercial baredie GaN power amplifier is used in addition to achieve the driving strength of up to 26 dBm at 7 GHz required for the target ODNP application. Moreover, the wide bandwidth of the custom-designed, printed MW Alderman-Grant (AG) resonator allows for an indirect measurement of the electron spin resonance (ESR) signal of the utilized DNP agent without the need for an additional ESR spectrometer. Overall, the presented system achieves an ODNP enhancement factor of 50 with an active volume of 500 nL, the latter number improving the state-of-the-art in chip-based ODNP platforms by a factor of 500×.