David C Liang

US Patent:

7115092, Oct 3, 2006

Filed:

Sep 18, 2003

Appl. No.:

10/667230

Inventors:

Byong-Ho Park - San Francisco CA, US
Friedrich B. Prinz - Menlo Park CA, US
David H. Liang - Menlo Park CA, US

Assignee:

The Board of Trustees of the Leland Stanford Junior University - Palo Alto CA

International Classification:

A61B 1/00

US Classification:

600143, 600139

Abstract:

A micromanipulator comprising a tubular structure and a structural compliance mechanism that are formed from a tube made of an elastic and/or superelastic material. Fabricated with laser machining and has no mechanical joints, the micromanipulator can be manipulated in various motions and degree-of-freedoms without permanent deformation. Shape Memory Alloys (SMAs) in one embodiment are implemented as main actuators of the micromanipulator. The micromanipulator can be implemented with multiple SMAs to manipulate the mechanism with multiple degree-of-freedom. In another implementation, multiple segments of the mechanisms are formed and arranged in various configurations, including a “double-helix”-like configuration, for enabling intricate motions of the micromanipulator. The micromanipulator is useful for intravascular interventional applications and particularly ultrasonic imaging when coupled with an ultrasound transducer.

US Patent:

8347738, Jan 8, 2013

Filed:

May 9, 2008

Appl. No.:

12/151963

Inventors:

Alexander Tung - Mountain View CA, US
Günter Niemeyer - Mountain View CA, US
David Liang - Menlo Park CA, US
Byong-Ho Park - Cincinnati OH, US
Friedrich B. Prinz - Woodside CA, US
Bob S. Hu - Stanford CA, US

Assignee:

The Board of Trustees of the Leland Stanford Junior University - Palo Alto CA

International Classification:

G01L 1/22

US Classification:

73862

Abstract:

This invention provides small position sensors for applications where localized sensing in a small volume of space is needed but where measurement of large relative displacement is also necessary. The invention enables a surgeon to accurately position the tip of a catheter during minimally invasive therapy. The current invention further improves the quality of tactile feedback to a physician during catheter-based surgeries with an axial force sensor at the tip of the catheter that allows for the transmission of force information to the physician. One embodiment of this invention is a position sensor for active interventional catheters, where the sensor may be laser-machined shape memory alloy (SMA), and the catheter actuators may be heated SMA or wire-pulleys. Providing position feedback from a catheter during minimally invasive therapy allows for closed-loop control of the catheter tip position under computer-aided guidance and enable force feedback to the physician.

US Patent:

20050267453, Dec 1, 2005

Filed:

May 25, 2005

Appl. No.:

11/137961

Inventors:

Serena Wong - Menlo Park CA, US
David Liang - Menlo Park CA, US
Girish Narayan - Sunnyvale CA, US

International Classification:

A61B018/04
A61B008/00

US Classification:

606027000, 600439000

Abstract:

A dual-mode, capable of imaging and ablation, ultrasound array integrated in a catheter is provided for minimally invasive treatment of arrhythmias. The catheter array is small enough for insertion through a peripheral vein and is longitudinally integrated with the catheter to have a side-view for tissue imaging and ablation. A high length/width array ratio creates a large aperture necessary for high power ablation densities. A catheter stabilization device maintains a distance between the catheter array and the wall of a heart or vein. Visualization of anatomy and imaging of ablated tissue provides a guide for placing the lesion and assists in achieving a pattern of ablated tissue. The catheter is advanced to another area by catheter rotation and/or array steering or focusing. Gating the imaging and ablation processes to a heart cycle allows for accounting and compensation of heart motion and enables automation of an arrhythmia treatment.

US Patent:

20060030777, Feb 9, 2006

Filed:

Jul 28, 2005

Appl. No.:

11/191311

Inventors:

David Liang - Menlo Park CA, US
Phillip Yang - Stanford CA, US
Aditya Koolwal - Potomac MD, US
Byong-Ho Park - San Jose CA, US

International Classification:

A61B 8/00

US Classification:

600437000

Abstract:

A technique for enhancing the image quality in intravascular ultrasound imaging increases contrast between blood and vessel wall processes image data using a point-wise t-statistic technique. Data from an ultrasound transducer is digitized and stored in a memory buffer [. For each point in the image, a t-statistic value is derived from signal amplitude values for the same point at a sequence of previous frames [. An image is then generated and displayed using the t-statistic values for the intensity of each point []. The improvement in contrast ratio as compared to averaging techniques is most significant at highly oblique angles when contrast ratio is particularly poor in the unprocessed signal.

US Patent:

56513666, Jul 29, 1997

Filed:

May 29, 1996

Appl. No.:

8/655034

Inventors:

David H. Liang - Menlo Park CA
Bob S. Hu - Menlo Park CA

Assignee:

Board of Trustees of the Leland Stanford Junior University - Palo Alto CA

International Classification:

A61B 812

US Classification:

12866206

Abstract:

A simple forward viewing ultrasound catheter includes one or more transducers and an ultrasound mirror supported by a bearing in a sealed end of a catheter with a drive cable imparting relative motion to the transducer and mirror. The mirror directs ultrasound waves forward of the catheter. An optical fiber can be provided to direct a laser beam for ablation of atheroma while under guidance of simultaneous intravascular ultrasound. A portion of a cavity can be simultaneously imaged while an interventional device operates on the imaged portion of the cavity.

US Patent:

56069758, Mar 4, 1997

Filed:

Sep 19, 1994

Appl. No.:

8/309540

Inventors:

David H. Liang - Menlo Park CA
Bob S. Hu - Menlo Park CA

Assignee:

The Board of Trustees of the Leland Stanford Junior University - Stanford CA

International Classification:

A61B 812

US Classification:

12866206

Abstract:

A simple forward viewing ultrasound catheter includes one or more transducers and an ultrasound mirror supported by a bearing in a sealed end of a catheter with a drive cable imparting relative motion to the transducer and mirror. The mirror directs ultrasound waves forward of the catheter. An optical fiber can be provided to direct a laser beam for ablation of atheroma while under guidance of simultaneous intravascular ultrasound.