Development of a Device for Neurochemical Sample Collection from Freely-Moving Monkeys Client: Dr. Ei Terasawa, Department of Pediatrics Advisor: Prof. Brenda Ogle, Department of Biomedical Engineering Group Members: Lauren Eichaker, Sarah Springborn, Ben Fleming, Cole Drifka, and Adam Pala

Presentation Outline Background (Research, Experimental Setup) Client’s Project Goals Current Design (Components, Problems) Current Problem Statement Product Design Specifications (PDS) Strap Design (Elastic Configuration, Hard Plastic Configuration, Nylon Configuration) Padding Design (Memory Foam, Silicone, Silicone-Memory Foam Combination, Air Bladder) Helmet Design (Existing Model, Conical Design, Boxing Helmet) Solution: Design Decisions Future Work (Tether System, Non-Specific Use) Ethical Considerations Credits Questions?

Background: Research Control of growth and development Brain’s role in triggering puberty Measures neuropeptides in hypothalamus for neuroendocrine studies Rhesus monkeys as model system for humans Associated Press. “Scientists Map Genome of Rhesus Monkey” 13 Apr 2007. 4 Mar 2008. <www.foxnews.com/story/0,2933,265907,00.html>.

Background: Experimental Setup Metal ring implanted into skull Microdrive unit attached Monkey transferred to chair Microdialysis probe inserted Tubing attached to fraction collector and pump Monkey confined to chair for 12 hours Forst SI, et al., Microdialysis methods for in vivo neropeptide measurement in the Stalk-median eminence in the Rhesus monkey, J Neurosci Methods (2007), doi: 10.1016/j.jneumeth.2007.09.001 SAEN. The Mary T. and Frank L. Hoffman Family Foundation. 11 Feb 2008. 4 Mar 2008. <www.all-creatures.org/saen/res-fr.html>.

Client’s Project Goals Construct protective device for microdrive unit Free monkey from chairing Protects microdrive unit from damage

Current Design: Components Cushion-and-Shell Design Three aluminum pieces: two base halves and porous cylinder Pieces fit together at an interface Silicone rubber interior protects the microdrive device Hose clamp secures the two base halves around interior Nylon straps for vertical stability Secured with zip ties Tether attaches to cylinder via custom interface

Current Design: Problems Ineffective weight distribution Currently 456.5 g Nylon straps do not contribute to support of device Adjustability Must be able to accommodate a wide range of monkey sizes

Current Problem Statement To improve on the device created last semester This involves the following: Weight reduction A more secure attachment around monkey’s head Better cushioning of the microdrive unit

Product Design Specifications (PDS) Safe for monkey Weight: under 500 g No sharp edges or toxic components Safe from monkey Able to withstand 100 N force Securely fitting and stable Promotes mobility

Strap Design: Elastic Configuration Pros: Accommodates various chin sizes and easy to adjust Under Armour would minimize discomfort felt by the monkey Cons: Monkey would be able to damage the apparatus Reduced degree of stability

Strap Design: Hard Plastic Configuration Pros: Monkey would not be able to damage or loosen Added foam would provide comfort for the monkey’s chin Cons: Very difficult to manufacture Would introduce extra weight and gaudiness

Strap Design: Nylon Configuration Pros: Easy to adjust in tiny increments Not much complexity in construction (zip ties) Cons: Wastefulness Puts pressure on facial nerves of the monkey

Strap Design: Design Matrix Security from Monkey (40) Ease of Use (15) Adjustability/Comfort (30) Ease of Construction (15) Total (100) Elastic – No Clasp 27 14 22 77 Hard Plastic with Foam 36 10 12 80 Nylon Reconfiguration 32 64

Padding Design The helmet design needs to fit snugly on a wide range of monkey head sizes The padding will play a large role in keeping the helmet design secure to the monkey’s head The padding of the design must also be relatively comfortable for the monkey The padding must be sufficiently lightweight

Padding Design: Memory Foam Pros: Highly customizable Easy and cheap to obtain Cons: Could pose a one-time use quality that would be wasteful Monkey could tear off foam and ingest it

Padding Design: Silicone Pros: Extremely protective of micro drive Provides exceptional stability to helmet device Cons: Silicone is, by nature, very heavy Does not adjust to fit different monkey head sizes

Padding Design: Silicone-Memory Foam Combination Pros Easy to obtain Relatively comfortable Secure Cons Not customizable to different monkey head sizes Heavy Expensive and wasteful

Padding Design: Inflatable Air Bladder Pros Most adjustable design Lightweight Easy to manufacture Cons May not wick away perspiration from monkey’s head May not be “monkey proof”

Padding Design: Design Matrix Safety from Monkey (40) Ease of Use (15) Adjustability/Comfort (30) Ease of Construction (15) Total (100) Memory Foam 27 13 28 14 82 Silicone 35 8 15 72 Combination (Memory Foam and Silicone) 30 9 19 12 70 Inflatable Bladder 31 26 84

Helmet Design: Existing Model Pros Available/modifiable Cons Too heavy for use No obvious way to further reduce weight Silicone insert is very heavy and the device is unwieldy in general Semi-specific use Straps did not serve their purpose A cutaway view of the current design displaying: the tree components, the silicone insert and the tether attached to the top.

Helmet Design: Conical Design Pros Addresses issue of being unwieldy Two-component design Opens up idea of using new materials Better center of gravity Cons Needs a strap system The Conical Design features a simple cone shape that needs straps to affix it to a monkey’s head.

Helmet Design: Boxing Helmet Design Pros Encases the monkey’s head Distributes the weight of the device evenly Two-component design Small strap: spanning only the chin Cons This could increase total weight Unique shape requires extra dimensions of the monkey’s skull Extra padding considerations This model would encase the monkey’s head. With a boxing helmet as the conceptual model, we will modify it to suit our needs.

Helmet Design: Design Matrix Weight (50) Ease of Construction (20) Safety (20) Ability to Withstand Force (10) Total (100) Boxing Helmet Design 42 15 18 9 84 Conical Design 40 7 83 Cylinder Design 30 19 16 6 71

Solution: Design Decisions Boxing Helmet Design Inflatable Air Bladder Roller-blade strap Still considering the use of a watch band as a strap Materials: either Titanium or a Polymer Still under investigation/consideration

Future Work: Tether System Majority of the weight located in the tether Need to reduce this weight to alleviate strain on the monkey’s neck Possibilities: Dual Swivel System Counterweight

Future Work: Non-Specific Use Ideally this helmet would fit monkeys from adolescence to adulthood Skull size and shape grow considerably during this time Current design incorporates an inflatable air bladder This can be altered to fit a variety of head sizes Still a great deal of variability

Ethical Considerations Research abides by strict federal regulations Monkeys under constant supervision and care Monkeys are not harmed or ill-treated during the experiment

Credits Dr. Terasawa Kim Keen Professor Ogle Primate Center Staff Last Semester’s Design Team

Questions?