Sensitive Optomechanical Ultrasound Sensor in an LED-Based, Low Fluence Photoacoustic Imaging System

Affordable and compact light sources, along with highly sensitive, broadband, low-noise sensors, are essential for enabling point-of-care photoacoustic imaging applications in resource-limited settings. Traditional systems use piezoelectric transducers, which often suffer from limited bandwidth and sensitivity, combined with solid-state lasers that are expensive and bulky. We present a potentially low-cost light-emitting diode (LED)-based photoacoustic imaging system featuring a highly sensitive optomechanical ultrasound sensor operating near thermomechanical noise limits. Utilizing a 620-nm LED, our setup delivers microjoules of pulse energy with 100-ns pulsewidths. We demonstrate its capability to resolve fine details through 2-D scan tomography, with minimal averaging for an effective sample rate of 100 Hz. Future improvements, including the development of larger LED arrays, multiplexed sensors, and on-chip integrated lasers, promise to enhance performance and further expand the technology's applicability.