A miniature ultrasound M-Mode imaging system based on time delay spectrometry

For wearable ultrasound applications, power and safety are a concern. We have developed an imaging method based on time-delay spectrometry (TDS) that employs a low-voltage, wideband chirp to establish a relationship between reflector depth and frequency by mixing the transmit and receive signals. We will show a low power, 4 channel ultrasound M-Mode system capable of tracking in vivo muscle interfaces in the forearm. The battery powered imaging system consists of power regulation subsystem, a RF chirp subsystem, and four channels consisting of a transmit RF amplifier, a mixing unit, and a receive amplifier which are sampled at 40 KSPS by a processor with a four channel ADC. The processor performs an FFT on each demodulated return to get 4 scanlines that are tracked over time to produce M-Mode images that are sent to a host computer. The wearable system can provide M-Modes images of up to 4 cm in forearm at a framerate of 50 Hz for ∼7 h with a total power consumption of 1.92 W. We demonstrate the ability of a miniaturized TDS ultrasound imaging system to collect in-vivo M-Modes that can be used for long term monitoring. The system can be used for wearable applications due to its low power consumption. [United States Department of Defense, Congressionally Directed Medical Research Program, award number W81XWH-16-1-0722 (PI: S Sikdar). National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under Award No. U01EB027601.]