Nanosecond pulsed current source for light emitting diode (LED) driven photoacoustic signal acquisition systems

Abstract Photoacoustic imaging (PAI) is gaining attention for its non-invasive diagnostic capabilities. Traditionally, bulky and expensive laser systems have been used as excitation light sources in PAI, posing challenges for translation and remote applications. High-power light emitting diodes (LEDs) can be an alternative light source. However, the necessary driver circuitry has not been extensively studied for driving the nanoseconds pulsed LEDs. This study develops and demonstrate for the first time the full circuit, performance, optimization and operating procedures of a Nanosecond Pulsed Current Source (NSPCS) to drive a high-power, high-speed LED array for PAI. The NSPCS driver can deliver tunable pulsed LED currents between 0-20 A, pulse widths of 50-100 ns, and trigger pulse repetition rates up to 20 kHz, achieving a driver efficiency of 58.27%. It can drive an array of 37 high-power LEDs (850 nm wavelength) with an electrical-to-optical efficiency of 24.8%. Illumination with this LED array produced a photoacoustic signal (after 79 dB amplification with low-noise amplifier) of 3.92 V (peak-to-peak) and a signal-to-noise ratio of 79.36 dB. The NSPCS circuit has demonstrated effective generation of tunable high-current pulses for LED-based PAI applications.