Parks Medical Electronics, Inc. (USA) - Non-imaging Doppler Ultrasound instruments, from Pocket Dopplers to complete Vascular Laboratories.

BabyBeat - Rents and sells fetal heart dopplers for home use.

SciMed Ltd (UK) - Manufacturer of transcranial Doppler and peripheral vascular Doppler equipment.

Multigon (USA) - Transcranial Doppler (TCD) - non invasive ultrasound technology used to evaluate blood flow velocity in the major basal intracranial arteries

DWL Elektronische Systeme GmbH (Germany) - manufacturer of transcranial and vascular Doppler devices.

Sonomed (PL) - Manufacturer of ultrasound medical diagnostic equipment (doppler devices).

Doppler Ultrasound - The Doppler effect is a change in the frequency of a wave, resulting from motion of the wave source or receiver, or in the case of a reflected wave, motion of the reflector. In medicine, Doppler US is used to detect and measure blood flow, and the major reflector is the red blood cell.

Ultratec (UK) - doppler medical devices

Spencer Technologies (USA) - Develops and sells products dedicated to noninvasive ultrasound monitoring of the brain such as digital transcranial doppler (TCD) and the Marc 600 probe fixation headframe.

Vmed Technology, Inc. - hand-held, 9V battery operated ultrasonic Doppler that has been used in human and animal applications for over 20 years. Models are available for fetal and blood flow detection both in humans and animals. Doppler signals are heard with a stethoscope style headset.

Sonotech (Germany) - Offers contract engineering services for ultrasound and spectral doppler development.