Sensors

As clinical ambitions continue to push the boundaries of surgery towards minimally-invasive and natural orifice techniques, the development of smarter and more sophisticated surgical platforms is essential. Endoscopy in particular allows for unparalleled access to confined locations within the body, at the cost of reduced transparency, complex ergonomics, and a lack of haptic feedback. In this work, I addressed the problem of fabricating high-quality, cost-effective sensors for endoscopic robotic applications by leveraging printed-circuit manufacturing techniques to fabricate a proprioceptive multisensor capable of angle, force, and temperature sensing with the goal of enabling closed-loop robotic control of tools passed through commercial endoscope working ports.

Broader Topics Explored: Origami-inspired design, circuit design, micro-manufacturing, sensor design, machine learning.

Proprioceptive multisensor design and fabrication: (a-b) kinematics model of linkage scaffold, (c) finite-element magnetostatics model, (d) sensor laminate post-manufacturing, (e) sensor populated with electronic componets, and (f) fold-pattern-guided assembly and realization of force sensing component.

Sensor linkage feasibility using a scaled-up model and real-time calibration via recursive least squares.

At-scale sensor linkage calibration and kinematic reconstruction

Through the course of my Ph.D dissertation work, I developed a variety of different sensors using printed-circuit MEMS fabrication techniques, exploiting numerous transductions mechanisms including foil-based strain gage, light-intensity modulation, capacitance sensing, and hall-effect sensing. An overview of this work is shown below (4 years of hard work compressed into a single image), c'est la vie).

A snapshot of PCMEMS sensors and structures I developed during the course of my dissertation: (a) grip force-sensing micrograsper with integrated foil strain gage-based half-bridge (b) three-axis force sensor with eight foil-based strain gages and a Maltese cross morphology, (c) three-axis light-intensity modulation-based force sensor with four emitter-detector pairs and on-board temperature and environmental irradiance sensing for disturbance rejection (d) capacitance-based force/displacement sensor with an integrated hydraulic actuator, (e) single-axis light-intensity modulation-based force sensor that ‘self-assembles’ via a pre-stretched spring (f) early prototype of an SMA-actuated flexure-based articulating scaffold with four emitter-detector pairs for light-intensity-modulation-based proprioceptive sensing.

Relevant Publications

A Highly Sensitive Capacitive‐Based Soft Pressure Sensor Based on a Conductive Fabric and a Microporous Dielectric Layer

Atalay, O., Atalay, A., Gafford, J. B., Walsh.

Advanced Materials Technologies (2018)

A Highly Stretchable Capacitive-Based Strain Sensor Based on Metal Deposition and Laser Rastering

Atalay, O., Atalay, A., Gafford, J. B., Wang, H., Wood, R., Walsh, C.

Advanced Materials Technologies (2017)

Distal Proprioceptive Sensor for Motion Feedback in Modular Roboendoscopic Systems

Gafford, J. B., Wood, R., Walsh, C.

IEEE Robotics and Automation Letters (2017)

Machine Learning Approaches to Environmental Disturbance Rejection in Multi-Axis Optoelectronic Force Sensors.

Gafford, J. B., Doshi-Velez, F., Wood, R. J., Walsh, C. J.

Sensors and Actuators A: Physical (2017), vol. 248, pp. 78-87.

Towards Medical Devices with Integrated Mechanisms, Sensors and Actuators via Printed-Circuit MEMS

Gafford, J. B., Kesner, S., Wood, R. J., & Walsh, C. J.

ASME Journal of Medical Devices (2016), 11(1).

Self-Assembling, Low-Cost, and Modular mm-Scale Force Sensor.

Gafford, J. B., Wood, R. J., & Walsh, C. J.

IEEE Sensors Journal (2016), 16(1), 69–76.

Soft pop-up mechanisms for microsurgical tools: design and characterization of compliant millimeter-scale articulated structures.

Ranzani, T., Russo, S., Gafford, J. B., Wood, R., Walsh, C. J.

Robotics and Automation (ICRA), 2016 IEEE International Conference on, Stockholm, Sweden.

A Monolithic Approach to Fabricating Low-Cost , Millimeter-Scale Multi-Axis Force Sensors for Minimally-Invasive Surgery.

Gafford, J. B., Kesner, S. B., Degirmenci, A., Wood, R. J., Howe, R. D., & Walsh, C. J.

Robotics and Automation (ICRA), 2014 IEEE International Conference on (pp. 1419–1425).

Force-sensing surgical grasper enabled by pop-up book MEMS

Gafford, J. B., Kesner, S. B., Wood, R. J., & Walsh, C. J.

IEEE International Conference on Intelligent Robots and Systems, 2552–2558.

Non-Cleanroom Fabrication of Carbon Nanotube-Based MEMS Force and Displacement Sensors

Cullinan, M., Panas, R., Daniel, C., Gafford, J.B., Culpepper, M. (2011).

ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, (Vol. 6). Washington DC.