1/4 PDS Syringe Dosing: Product Design Specifications (PDS) Title: Syringe Dosing Team Members: D Elese Hanson D Christine Weisshaar D Andrew Wentland Date: May 4, 2005 Function: The device will accept a standard 1 cc syringe of " diameter and automate the process of measuring and delivering medication. After a syringe is inserted into the device, a user can type in the number of units that should be drawn into the barrel of the syringe. The user will then insert the needle into a bottle of medication, such as insulin, and press the "Fill" button. A motor will drive the syringe's plunger back via a screw mechanism, drawing the medication into the barrel. Afterwards, the user will insert the needle into the body and press the "Inject" button. The motor and screw will drive the plunger in and push the medication into the user. Since the only manipulation required by the user is pressing numbers on a keypad and inserting the needle into the body, the amount of dexterity is reduced dramatically. Client Requirements: D The device should accept 1 cc syringes " in diameter. D The device should dose to the nearest 0.01 cc. D The device should be easy to use for people with poor vision, low dexterity, diminished motor control, Parkinson's, and/or other neuromuscular disorders. Design Requirements: 1. Physical and Operational Characteristics a. Performance requirements
PDS 2/4 i. On average, the device will be used twice daily with slow-acting insulin and several more times with fast-acting insulin to accommodate the eating habits and varying blood sugar levels of the user. ii. The device will be modeled to fit BD Ultra-Fine II 1 cc syringes (BD has 75 80% market share). iii. The device should be easy to use for people with poor eyesight and/or dexterity. b. Safety i. Standard syringe safety measures should be taken, including proper sterility procedures and disposal. ii. The device will contain batteries, so the batteries should not be left in the device if they have exceeded their expiration date. iii. Being electronic, the device should comply with FCC standards. c. Accuracy and Reliability i. The device will use 1 cc syringes and dose to the nearest unit, where a unit is
1
/100 of a cc.
ii. With the stepper motor in the prototype, the shaft of the motor can move in steps of 1.8. In initial testing, 300 steps of the motor corresponded to 1.06 units being expelled from or drawn in to the plunger. Therefore, the prototype is accurate to a minimum accuracy of 1/100 of a cc. iii. This accuracy will be true as long as the syringe dimensions, screw pitch, and motor increments do not change. d. Life in Service i. The device should function for at least five years around five times per day at five minutes per usage under normal functionality (low-viscosity fluid, such as insulin, and careful handling). e. Shelf Life i. Being electronic, the device should not be left in the sun or in freezing Direct temperatures. contact of the electrical components with liquids should be avoided.
PDS 3/4 ii. The batteries should not be left in the device for more than three years or beyond their expiration date, whichever comes first. f. Operating Environment i. The device should operate and remain accurate at temperatures above freezing and below 100 F. ii. The device should not be affected at different pressures or humidity. iii. The device will be inoperable if dust, dirt, or water has gotten into the device. iv. The device can be used by able people of any age above seven. g. Ergonomics i. This device seeks to overcome the typical problems that patients with poor muscular control, tremors, Parkinson's, and poor eyesight have operating a syringe. ii. Anyone who has some control of the hands should be able to use the device, because the device only requires the pressing of a few buttons with low resistance. h. Size i. The device should fit into a single hand. ii. The device should not exceed the length of two syringes (~10") or a width of 3". iii. It should be completely portable, such as being able to fit into a purse. i. Weight i. Ideally, the device should weigh less than a pound. j. Materials i. There are no restrictions on the materials, although non-slippery materials are best. ii. Materials that are smooth are ideal, so as to ensure comfort of the user. k. Aesthetics i. The color of the device should be mild, so as not to attract attention. A colorful appearance may bring too much attention to a user that prefers discretion. ii. The device should have a smooth texture, but not too smooth to slip out of the hands. Rubber grips in key locations would be best. iii. The device should contour to the hand in a natural fashion.
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