Concept Generation

Introduction

Concept generation is the part of the project when the team finally gets to use its creativity to develop innovative solutions to meet the customer's needs. Once the critical subproblems were identified, the group developed and examined various ideas to address each of the subproblems. Next, the group combined the solutions to the critical subproblems to generate some potential full device solutions.

Decomposition of Design Problem

The intent of this project is not necessarily to design any new technologies, but rather to combine existing technologies and solutions in a novel way to accomplish a specific task. The device is attempting to emulate the actions that human would take to dose a syringe. Consequently, the problem does not lend itself naturally to functional decomposition; breaking down the problem by sequence of steps allows each step in the process to be addressed as its own subproblem, and product concepts consist of various combinations of mechanisms that would accomplish the task of dosing a syringe.

Figure 1: "Black Box" Functional Diagram

Figure 2: Functional Diagram Showing Subfunctions

Concept Breadth and Diversity

To explore various means for accomplishing critical subproblems, concept classification trees are used diversify different solutions.

Syringe Loading

Figure 3: Concept Classification Tree for Syringe Loading

Each injection requires a new syringe which must be loaded by the user. Loading can be achieved by either securing the syringe with form or force-fitting constraints. Form-fitting constraints include a clip into which the syringe barrel could snap. Similarly, a cylindrical opening as wide as the syringe diameter, a fitting for the syringe wings, and a latching mechanism would also take advantage of various aspects of the syringe geometry for loading. On the other hand, more general securing mechanisms such as a spring-loaded latch or ball bearing would load and secure the syringe without a dependence on the syringe form.

Bottle Loading

Figure 4: Concept Classification Tree for Bottle Loading

Like the syringe, the insulin bottle must be loaded by the user. Again, either a form or force-fitting constraint could be utilized.

Addressing Bubbles

Figure 5: Concept Classification Tree for Bubble Addressing

Bubbles in the syringe after dosing must be eliminated to prevent misdoses. Slowly withdrawing the syringe plunger when dosing may prevent bubble formation entirely. However, if this technique is not feasible, a bubble detection and removal system, or simply a removal mechanism could be used. Bubbles can be detected using several transducers that measure changes in a uniform insulin volume when bubbles are present. Capacitative, ultrasonic, and photoelectric transducers could be utilized in this way. The simplest removal mechanism would involve overdrawing a known volume of insulin, forcing the bubbles into this volume, and expelling them. Multiple dose withdrawal, tapping, or a piezoelectric transducer could also be used to remove bubbles.

Syringe Dosing

Figure 6: Concept Classification Tree for Syringe Dosing

In order to dose the syringe, the plunger must be mechanically retracted a specific distance. Either a pneumatic, hydraulic, or electric system could perform this operation. Of these, an electrically driven system offers the most options. A linear or rotational motor could be used to power various mechanisms for actuating the syringe plunger.

User Interface

Figure 7: Concept Classification Tree for Getting Dose Input from User

The user requires an interface to enter the insulin dose desired. A dial, up/down buttons, and a numeric keypad would require the user to physically enter the dose. A dial or up/down buttons would increment by a single insulin unit (0.01 cc), while the exact amount could be entered using the keypad. Finally, a hands-free dosing input could be achieved using voice recognition hardware or mental telepathy.

Bottle Mixing

Figure 8: Concept Classification Tree for Mixing Cloudy Insulin

Before injecting long-acting insulin, the insulin in the bottle must be mixed to a uniform consistency. Either the bottle itself can be shaken in a cyclical pattern to mix the contained liquid, or the liquid itself internally mixed with the bottle stationary. Bottle movement rotationally and translationally can achieve mixing by controlling the frequency and duration of the movements. Internally, repeated drawing and expulsion of insulin with the syringe, or the activation of a magnetic stirring pill would also mix the insulin.

Promising Critical Subproblem Concepts

Combination 1

Drawing 1: Concept Combination Table and Drawing for Syringe Manipulation

Drawing 1 shows the lid method for bottle loading, which involved dropping the bottle into a cylinder and securing it with a lid. Loading the syringe is accomplished by using a spring loaded ball bearing method that will clasp the syringe in a syringe-shaped form. The syringe is then connected mechanically to a screw, which, when turned by an electric motor, will create an accurate dosing mechanism.

Combination 2

Drawing 2: Concept Combination Table and Drawing for Syringe Manipulation (alternative combination)

Drawing 2 features a rack and pinion system driven by a gear connected to an electric motor to control the syringe plunger movement. A molded rubber boot holds the syringe in a fixed position. A piezoelectric transducer is clamped on to the end of the syringe and vibrates to break bubbles loose.

Combination 3

Drawing 3: Concept Combination Table and Drawing for Bottle Manipulation

Drawing 3 displays the possibility of using a magnetic lid for storing the bottle and keeping it properly aligned. The bottle can then be mixed by using a single, motor-driven wheel to rotate the bottle about its axis. The syringe is loaded externally, snapping into rubber-coated clips which prevent the syringe from unwanted movement.

Combination 4

Drawing 4: Concept Combination Table and Drawing for Bottle Manipulation (alternative combination)

Drawing 4 shows a method for combining bottle loading and bottle mixing into a single mechanism. The internal case has two openings which can each hold a bottle. The case can be turned easily because it is separated from the external casing by ball bearings. Opposite from the loading side, the syringe may load into the bottle. This mechanism allows for storing two different types of insulin bottles simultaneously, which is a necessity for most diabetics.