PMC

A setup of the frequency response calibration of the electric network by using a thermal voltage converter and oscilloscope for voltage correction applied to the ultrasonic transducer.

Custom electronic manometer. This system requires a custom-built analog-to-digital converter system. The thoracentesis catheter is connected to a hemodynamic transducer which in turn is connected to a custom-built analog-to-digital converter that filters and interprets the information as pleural pressures.

(a) A 3D CAD rendering of the plastic shell used to hold the transducers. (b) A 3D sketch of object space in relation to plastic shell. (c) Photograph of a custom-built transducer (left) and front face of the transducer (right). The red scale bar represents 1 cm. (d) Example of a photoacoustic pressure signal from a photoacoustic point source (~100 μm) averaged over 5 triggers acquired with one transducer at 40 MHz sampling rate. The amplitude represents the counts on the digital converter and ranges from ±2048 counts.

Comparing the noise of the voltage reference and the capacitive transducer at 0.1 Hz with the same maximum output of 5 V. The red line comes from the capacitive transducer and the blue one is caused by the DC source being kept constant at 4.6 μV/Hz^1/2 at 0.1 Hz. The black line is the background noise of the 24-bit analog-digital converter (ADC).