Northwestern University Feinberg School of Medicine

Northwestern University Prosthetics-Orthotics Center

PORTAL-Prosthetic and Orthotic Technology Assessment Lab

The Prosthetic and Orthotic Rehabilitation Technology Assessment Laboratory (PORTAL) is used for in vivo evaluation of upper and lower extremity prosthetic and orthotic devices, both commercial and experimental. Within PORTAL are 3 specialty labs: 
  1. Functional Physiology Testing Lab 
  2. Mechanical Testing Lab 
  3. Rapid Prototyping Lab 

Functional Physiology Testing Lab 

The Functional Physiology Testing Lab is equipped with an XSens Inertial Measurement Unit system to capture instantaneous body segment accelerations and rotations. The lab also has a Cosmed Sport Treadmill (T170) with a large belt surface, safety harness, incline/decline capabilities, and adjustable handrails. 

Mechanical Testing Lab 

The Mechanical Testing Lab contains equipment that tests the mechanical properties of components and materials used in our research projects. This lab contains an Instron 8800 Materials Testing Machine that is described below. 

Material Testing Machine 

The mechanical properties of materials and components are determined using an Instron 8800 (Instron Corp, Norwood, MA) Materials Testing Machine. This system uses hydraulic actuators to apply loads in cyclical or linear patterns to the specimens. These applied loads, which are controlled using feedback loops, are measured using either a 10,000-pound, 1,000-pound, or 110-pound load transducer. A data acquisition program connected to the Instron system acquires the loading response information and creates stress-strain diagrams for a material. Using custom adaptors and fixtures, this system can also perform all of the mechanical tests detailed in the American Orthotic and Prosthetic Association Prosthetic Foot Project Report: 
http://www.aopanet.org/wp-content/uploads/2013/12/Prosthetic_Foot_Project.pdf

Rapid Prototyping Lab 

The Computer-Aided Design and Manufacturing (CAD/CAM) Laboratory is equipped with a Stratasys Fusion Deposition Modeler (FDM) 400mcTM. This rapid prototyping machine uses data in the form of stereo lithography (STL) files that computers can use to make 3-dimensional objects such as prosthetic sockets. Fabrication is fully automatic and uses a dispensing nozzle to deposit thin layers of liquefied plastic that quickly hardens into a solid. This equipment allows researchers to rapidly fabricate prototypes, thus enabling early error correction and prediction of end product performance.

Provel d1 Mechanical Digitizer and Shapemaker Software 

The CAD/CAM Lab is also equipped with a Provel d1 mechanical digitizer and Shapemaker software. The mechanical digitizer measures the dimensions of a cast or mold of the residual limb and transfers the data to the Shapemaker software, which creates a three-dimensional computer model. This computer model of the residual limb is modified digitally to relieve pressure in sensitive areas and apply pressure in tolerant areas. When modification is completed, a data file with positional instructions can be sent to systems like Squirt Shape and Stratasys for fabrication.

We utilize these time and labor saving CAD/CAM resources in many of our projects, including socket development and gait studies of amputees that require multiple prostheses per subject. CAD/CAM enables easy, iterative modifications to socket shape and rapid fabrication of prosthetic sockets.