Progress Report: A Wearable TMS System for Ambulatory Use By: Ben Sass Group 19: Beller, Kahan, Sass Client: St. Jude Medical Date 10/25/2014

Project Scope and Need  TMS – Transcranial Magnetic Stimulation  AC current through a coil creates a magnetic field.  This magnetic field alters neuronal activity in the brain.  Need: Therapy + TMS  Need: Future Home Therapy

Wearable TMS System Maintaining Coil Position Material Polystyrene Polycarbonate Urethane Thermoplastic Elastomer Headgear Hemispherical shell Modular Plate System 3D printed bonnet Coil Interface Manipulator Track System Direct attachment Targeting Mechanism Anatomical Landmark MRI Marker Stereotactic Tracking Design Overview

Design: Material NinjaFlex®: Thermoplastic Elastomer Polycarbonate Urethane Polystyrene Manufacturing 3D Printing (moderate-difficult) 3D printing (easy- moderate) Extrusion (easy) Ease of Cleaning Mild soap Mild alcohol Hardness 85A75DM60-90 Elongation >500%241%3-4% Young's Modulus 15.2 M-Pa (2200 psi)260 M-Pa M-Pa ( psi) Ultimate Tensile Strength 34.5 M-Pa (4000 psi)63.2 M-Pa (9171 psi) M-Pa ( psi) Density g/cc g/cc g/cc Table 1: Properties of Materials for Headgear Design

Pugh Chart: Part A WeightMaterial PolyurethaneNinjaFlex®Styrofoam Cost48510 Portability8910 Durability51097 Reprocessing Rate Spatial Resolution 10 8 Lightweight88108 Patient Comfort 8699 Target Precision 10 3 Ease of Setup

Headgear: Hemispherical Shell Hemisphere system with Track Hemisphere system with grid

Headgear: Modular Plate System  More individualized  Good fit for variety of head sizes  Velcro ® is used to connect plates  Grid system  A manipulator will be used for fine coil placement

Headgear: 3D Printed Bonnet  Highly Individualized  Expensive  Time Consuming Steps: 1. Scan/image the head 2. Convert images to model 3. Convert surface model of head to model of bonnet 4. Print the bonnet

Pugh Chart: Part B WeightHeadgear Design Hemi ShellPlate SystemCustom Bonnet Cost410 1 Portability810 Durability5855 Reprocessing Rate 6855 Spatial Resolution 1048 Lightweight8510 Patient Comfort8410 Target Precision 108 Ease of Setup

Coil Interface: Grid & Track System Hemisphere system with TrackHemisphere system with grid

Coil Interface: Motorized Manipulator  The coil manipulator is a 2 stage linear rail system.  Biaxial Movement (normal to the head surface)  Feedback to maintain optimal coil position  Magnetic or potentially piezoelectric

Pugh Chart: Part C WeightManipulator MotorizedManualTrack System Cost4364 Portability810 7 Durability5572 Reprocessing Rate 6109 Spatial Resolution Lightweight8886 Patient Comfort 8996 Maximum Operation Time Target Precision Ease of Setup

Targeting: Anatomical Landmarks  Anatomical Landmarks  Locate target based on:  Target correlation with observable patient function  Approximate distance from one of the ‘Reporter Regions’  Not very accurate Fitzgerald, Paul B., et al. "A randomized trial of rTMS targeted with MRI based neuro-navigation in treatment-resistant depression." Neuropsychopharmacology 34.5 (2009):

Targeting: MRI-Marker System  fMRI to locate areas of abnormal activity  Contrast agent attached to coil in ‘V’ shape.  Trivial computational analysis leads to correlation between coil position and orientation of the marker  More accurate, but confined to MRI machine Yau, Jeffrey M., et al. "Efficient and robust identification of cortical targets in concurrent TMS–fMRI experiments." NeuroImage 76 (2013):

Targeting: Frameless Stereotactic Tracking Mechanism  Fixed collection of cameras placed to track coil position in relation to an fMRI image  Allows for construction of a 3D model of marker position  Interacts well with live feedback positioning  Limited within a visual field Schönfeldt-Lecuona, Carlos, et al. "Accuracy of stereotaxic positioning of transcranial magnetic stimulation." Brain topography 17.4 (2005):

Pugh Chart: Part D WeightTracking MRI Marker Stereotactic Camera Anatomical Landmark Cost4103 Portability83710 Durability5109 Spatial Resolution 10 1 Target Precision Ease of Setup

Final Solution  Modular Plate System  NinjaFlex ®  Motorized Coil Manipulator with Screw Interface  Commercially available stages  Grid System ~1.25 cm  Stereotactic Targeting system

Acknowledgements  I’d like to thank  Mr. Rosenberg and Dr. Venkatesan  Zach and Lindsey  Professor Mell  Dr. Klaesner  Rebecca Gilson for their help with this presentation.

Thank you!  Any questions?