Medical Devices
Clinicians: Ogonna Kenechi Nwawka, MD
Engineers: Daniel Sturnick, MS
Overview: The constant force probe handle is a device designed to standardize and directly control contact force at the transducer-patient interface. The handle allows the transducer head to displace along a low-friction path separately from the operator’s hand position while maintaining a constant force applied by the spring, independent of operator’s hand position. The design is 100% mechanical and is comprised of a spring and pulley system within an outer casing.
Clinical Problem: Ultrasound technology is widely used in the field of medicine in both diagnosis and treatment. An ultrasound protocol growing in popularity is shear wave elasticity, which can assess the mechanical properties of tissue (e.g., stiffness) and has been used in the diagnosis of liver fibrosis, breast cancer, and, recently, various musculoskeletal tissue pathologies. One challenge faced is that outcomes of ultrasound diagnostics, particularly evident in shear wave elastography, is sensitive to the applied force between the sonographer and the subject. This leads to variability within an exam and difficulty in reproducing the same results in a subsequent exam, particularly if performed by a different sonographer. For example, in liver fibrosis detection, the apparent morphology and stiffness outcomes from shear wave imaging of the fibrosis are affected by the pressure imparted by the operator on the probe and could lead to a misdiagnosis or a false positive.
Technology: The constant force probe handle is a device designed to standardize and directly control contact force at the transducer-patient interface. The handle allows the transducer head to displace along a low-friction path separately from the operator’s hand position while maintaining a constant force applied by the spring, independent of operator’s hand position. The design is 100% mechanical and is composed of a spring and pulley system within an outer casing.
The handle permits control of a wide range of applied forces by use of interchangeable constant force springs with various specifications, allowing the clinical use case to dictate what target force control is required. The invention is intended to accommodate constant force spring specifications ranging from anywhere from sub-Newton loads to hundreds of Newtons.
Differentiation: While there is no known commercially available controlled-force probe handle, there have been inventions conceived in this space that utilize an external control module. The key differentiator of the CF Probe is that it is mechanical in nature and does not require a feedback loop between the measured force and the actuator that responds to the measured force. The CF Probe is a simpler, more intuitive and reliable solution that requires no electric components or calibration.
Proposed Application/Integration: The CF Probe can be integrated with any ultrasound system. The patent covers designs where an external handle enclosure surrounds an existing probe and where the mechanism controlling the force is incorporated inside a probe. As there are no actuators or instrumentation that need to be incorporated, the exterior handle enclosure grip can be designed to be ergonomic so the examiner may perform examinations with comfort and consistency.
Legal Status: Patent pending (PCT Application: WO 2018/119127 A2)
