Nonlinear system identification techniques and devices for discovering dynamic and static tissue properties

• US 9,517,030 B2
• Filed: 06/20/2014
• Issued: 12/13/2016
• Est. Priority Date: 09/01/2009
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Hunter, Ian W., Chen, Yi
• Primary Examiner(s): Stout, Michael C
• Assistant Examiner(s): Kolderman, Nicholas E
• Application Number:
  US14/310,744
• Publication Number:
  US 20150051513A1
• Time in Patent Office: 907 Days
• US Class Current: 1/1
• CPC Class Codes: A01G 7/00 Botany in general
• CPC Class Codes: A61B 5/0048 Detecting, measuring or recording by applying mechanical forces or stimuli A61B5/021, A61B5/4884 and A61B9/00 take precedence
• CPC Class Codes: A61B 5/0053 by applying pressure, e.g. compression, indentation, palpation, grasping, gauging
• CPC Class Codes: A61B 5/0055 by applying suction
• CPC Class Codes: A61B 5/0057 by applying motion other than vibrations, e.g. rolling, rubbing, applying a torque, tribometry
• CPC Class Codes: A61B 5/103 Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes A61B5/08 takes precedence; measuring aids for tailors A41H1/00; measuring instruments specially adapted for dentistry A61C19/04
• CPC Class Codes: A61B 5/442 Evaluating skin mechanical properties, e.g. elasticity, hardness, texture, wrinkle assessment
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 9/00 Instruments for examination by percussion; Pleximeters
• CPC Class Codes: G01N 2203/0069 Fatigue, creep, strain-stress relations or elastic constants
• CPC Class Codes: G01N 2203/0218 Calculations based on experimental data
• CPC Class Codes: G01N 2203/0246 Special simulation of "in situ" conditions, scale models or dummies
• CPC Class Codes: G01N 2203/0278 Thin specimens
• CPC Class Codes: G01N 3/24 by applying steady shearing forces G01N3/26, G01N3/28 take precedence
• CPC Class Codes: G01N 3/40 Investigating hardness or rebound hardness

Abstract

A device for measuring a mechanical property of a tissue includes a probe configured to perturb the tissue with movement relative to a surface of the tissue, an actuator coupled to the probe to move the probe, a detector configured to measure a response of the tissue to the perturbation, and a controller coupled to the actuator and the detector. The controller drives the actuator using a stochastic sequence and determines the mechanical property of the tissue using the measured response received from the detector. The probe can be coupled to the tissue surface. The device can include a reference surface configured to contact the tissue surface. The probe may include a set of interchangeable heads, the set including a head for lateral movement of the probe and a head for perpendicular movement of the probe. The perturbation can include extension of the tissue with the probe or sliding the probe across the tissue surface and may also include indentation of the tissue with the probe. In some embodiments, the actuator includes a Lorentz force linear actuator. The mechanical property may be determined using non-linear stochastic system identification. The mechanical property may be indicative of, for example, tissue compliance and tissue elasticity. The device can further include a handle for manual application of the probe to the surface of the tissue and may include an accelerometer detecting an orientation of the probe. The device can be used to test skin tissue of an animal, plant tissue, such as fruit and vegetables, or any other biological tissue.

Claims

1. A device for measuring a mechanical property of a tissue, the device comprising:

a probe configured with a probe surface for contacting a surface of the tissue;

an actuator coupled to the probe for moving the probe laterally with respect to the surface of the tissue;

a detector configured to measure a response of the tissue to the lateral movement of the probe; and

a controller coupled to the actuator and the detector, the controller configured to move the probe laterally with respect to the surface of the tissue by driving the actuator using a stochastic sequence and determine the mechanical property of the tissue by using the measured response received from the detector when the stochastic sequence is driving the actuator.

2. The device of claim 1, wherein the actuator is a Lorentz-force actuator.

3. The device of claim 1, wherein the mechanical property is indicative of tissue compliance.

4. The device of claim 1, wherein the mechanical property is indicative of tissue elasticity.

5. The device of claim 1, wherein the detector comprises a force sensor for detecting force of the lateral movement.

6. The device of claim 5, wherein the force sensor comprises a current sensor for detecting a current input to the actuator.

7. The device of claim 1, wherein the detector comprises a position sensor for detecting displacement of the tissue surface.

8. The device of claim 1, wherein the controller is configured to employ system identification to determine the mechanical property of the tissue from the measured response to the stochastic sequence driving the actuator.

9. The device of claim 8, wherein said system identification is nonlinear system identification.

10. The device of claim 8, wherein the stochastic sequence is a Gaussian input.

11. The device of claim 8, wherein the stochastic sequence is a Brownian input.