Concept Designs
The initial goals of this project were to construct a device that would function similar to a Mr. Coffee kitchen appliance. In theory you could awaken to a pot of coffee and your morning medications. Here we present our intentions for the manufacturing of a home medication dispenser.
Care should be taken to make the dispensing apparatus compatible with as wide a range of input pill dimensions as possible. This means that both the pill dispenser and pill cutter must accommodate pills of a generic size. It would be much easier to accommodated pills of a specific size, a simple pill dispenser and cutter could be fashioned using a slotted hole.
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| Here is a very simple design for a design that integrates the pill selector and cutter into one simple unit. This would work very well for one specific type of pill. Since we believe a typical user takes more than one type of medication, a more generic approach to the pill selection and cutting process must be taken | |
Possible Pill Unit Dispenser Designs
Corkscrew Design Concept:
To address the primary problem of pill stacking in the Gate Design, an incrementally more complex solution was pursued. This second mechanism we investigated for dispensing pills is based upon a patented dispenser design detailed in the text of U.S. Patent 68604031.
Although we are not certain that we understood the device in its entirety, partially because of the cryptic nature of its text, two illustrations from the patent which we interpreted are shown in Figure 41.
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| Figure 4: (left) Illustration of container with apparent spiral cut tracks along with pills travel. (right) Illustration of container that shows the cone that pushes pills out to the sides of the container. Also shows the holes at the end of tracks through which pills fall to be dispensed. Edited from1. |
The left illustration appears to show a pill container into which a series of “tracks” have been cut, along which pills are conveyed in single file1. The patent text implies that vibration of the apparatus can be used to help move pills along1. The right illustration seems to show how a small opening can be made at the bottom of a track to let out a single pill at the end, and how a cone-shaped protrusion can be used to ensure pills are pushed towards the walls of the container1.
Perhaps the most important idea gleaned from this design was that of using a track to line pills up in single file1. This action, at least in theory, increases the consistency with which the dispenser operates over that of the Gate Design, where pills might be stacked upon each other near the opening gate in an unknown manner1. Although this track concept was clearly appealing, the question of where the track could be placed in our dispensing system was a somewhat difficult question to answer1. A helical track, initially, seemed like it would require a significant amount of volume and material, and therefore integrating it into the prescription bottle appeared undesirable, because of the likely effect on disposable component cost, and because the available space in the bottle for holding medication would be decreased. However, integrating the track into the dispensing device presented its own difficulty, which was brought up by the group industry mentor.
If the track was integrated into the dispensing device, and a user needed to remove a bottle before all of its medication had been dispensed by the machine, pills would be left stuck inside the interior of the device. This not only would prevent the user from recovering all of their medicine, but also preclude the insertion of a bottle containing a different medicine in the same container slot occupied by the previous bottle. The only possible remedy contemplated was some sort of flushing mechanism to quickly get pills out of the device, but such a mechanism would likely be inconvenient to use, and create the risk of medication overdose resulting from accidental activation of the mechanism.
Being very interested in the pill track concept, and realizing that the issues involved in track placement could not be completely eliminated, we formulated a design that integrated the track into the disposable component, and merely minimized the negative aspects of this design decision. The “insert” portion of the resulting “Corkscrew Design”, analogous to the part with the same name in the Gated Design, is shown in Figure 5. To minimize the height of the insert, the helical cut used to form the pill track was able to be made reasonably shallow. Even though his idea was not directly implemented in the Corkscrew Design, the industry mentor also realized that the length of the track could probably be considerably less than a full helical revolution and still carry out its function of lining pills up reasonably well. An additional feature included by the industry mentor, carried over from the patented design, is the shallow cone present on the end of the insert which faces into a prescription bottle, the purpose of which is to drive pills radially outward towards the pill track1.
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| Figure 5: Conceptual illustrations of the “insert” that would be attached to a prescription bottle cap in an implementation of the “corkscrew” design. Based on1 |
Figure 6 shows how the corkscrew insert and customized cap would be fitted with a standard prescription bottle. Providing a full explanation of how pills are dispensed with the corkscrew mechanism is complicated by the fact that there is more than one way it can be operated.
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| Figure 6: Conceptual illustration of how corkscrew insert and cap would be integrated with a standard prescription bottle. Based on1 |
Similarly to how we perceived the patented design worked, the prescription bottle can be inverted, the insert kept static, and vibration can be used to shake pills down the corkscrew track and out the opening in the cap1. However, as the prescence of a snap hook and hexagonal hole similar to those in the Gated Design suggest, one can also rotate the insert with respect to the cap to actively push pills out of a bottle with the corkscrew threads. We postulated that dispensing pills by rotating the corkscrew insert would result in more controlled pill release than was possible with the Gated Design. This was because we envisioned that the prescription bottle could be oriented at only a slight incline, to mitigate the instability we associated with gravity, and still be capable of dispensing pills, since the corkscrew threads could push pills in the horizontal direction. In other words, we thought the turning corkscrew mechanism could be set up so that a motor under our control, instead of gravity, would be providing the force that ejected pills, and that this meant it was less likely that, as in the Gated Design, the release of one pill could immediately leave a void through which another could escape (testing showed this reasoning to be somewhat flawed, as explained later). To evaluate the merits of either method of dispensing pills with the Corkscrew Design, a prototype device needed to be constructed.
Corkscrew Design Implementation:
With the conceptual details of the Corkscrew Design worked out, our industry mentor was able to fabricate a prototype exhibiting the design’s essential features. A photograph of the prototype is presented in Figure 6, with the opening corresponding to the hole in the cap facing upward. The corkscrew insert can be seen as the green structure encased in the transparent “prescription bottle”. There is a small black protrusion from the top of the prototype, which is the end piece of an axle through which the insert can be rotated. It contains a hexagonal port that allows the axle to be turned with an Allen wrench. Dimensions that may be of interest are those of the cross-section of the (in Solidworks™ terminology) “spiral cut” used to form the pill track. In the prototype shown, the cross section is a square with a side-length of 7.5mm. This cross-section was large enough for only some of the pills procured for testing purposes, but nonetheless was adequate to allow us to evaluate the methods we considered for dispensing pills with the Corkscrew Design using the fabricated prototype.
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| Figure 6: Prototype corkscrew dispensing mechanism fabricated by industry mentor. Based on1 |
Corkscrew Design Testing:
Fortunately, the group was able to assemble a “testing rig” that enabled more rigorous testing of the Corkscrew Design than that carried out to evaluate the Gate Design. Figure 19 shows the apparatus. The wooden framing was constructed by the Biological Sciences Machine Shop at the University of California, Irvine. The corkscrew prototype is anchored to a wooden beam along with two electric
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| Figure 7: Photograph of Corkscrew Design Testing Rig. Based on1 |
motors. The topmost motor has an asymmetric load (fashioned by our industry mentor) which allows the motor to act as a vibration source. The lower motor is used to rotate the corkscrew insert. Because of the mass of the insert and its frictional interactions with the container, the torque provided by the output shaft of a “naked” dc motor was inadequate to produce rotation. A “gearbox kit” bought from an electronics store was assembled and proved capable of providing the necessary torque. It was possible to test operation of the prototype at different incline angles by simply holding the rig on its side. The setup allowed the group to evaluate dispensing pills from the prototype through simultaneous rotation of the insert and vibration of the container, as well as through use of vibration alone with the container completely inverted.
In our initial testing of the rotating insert mechanism, the prototype was situated at a shallow incline, and the insert was rotated such that the threads of the corkscrew advanced towards the closed end of the container, corresponding to the “top” of an actual prescription bottle. It was quickly discovered that a major issue with this mechanism was that pills could easily become trapped between the corkscrew thread and the surface of the closed container head, jamming the device (as illustrated in Figure 8). Vibration of the container lowered the frequency of jamming but did not eliminate it. In addition, it was found that, just as in the Gated Design, multiple pills often fell out nearly simultaneously. It is believed this was possible because even within the pill track, pills could become stacked one on top of the other.
The failure to fully anticipate this problem resulted from a misconception about how the corkscrew threads would actually advance pills. Even though when the corkscrew is rotated, the threads appear to travel horizontally, in reality they do not, and pills advance by repeatedly being carried upwards by the threads and then “falling” along the surface of the corkscrew. That is, the corkscrew threads do not directly push pills horizontally. Pills only move horizontally because they fall down the sloped surface presented by the corkscrew threads. Therefore even though the net path taken by pills as they are dispensed by the rotating corkscrew may be shallow, the actual path involves repeated vertical displacements. As a result, a pill immediately “behind” another in the corkscrew will naturally rest on top of the first. Like in the Gate Design, when the corkscrew rotation finally presents one pill with a path through which it can leave the container, pills stacked above it can quickly follow.
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| Figure 8: Pills becoming jammed in the prototype device between the corkscrew thread and the bottom of the container. Based on1 |
As stated before, our apparatus also allowed us to test operation of the corkscrew in a manner similar to that we believed is described in the patent text provided by Mehrens et. al.1. To test this mechanism, the prototype container was held completely vertical, and the insert was statically positioned so that the end of the pill track was over the sector-shaped opening. A knob-operated variable resistor was used to run the vibration motor at different power levels, which was (roughly) directly proportional to how fast pills were conducted down the pill track. We conducted some simple quantitative testing of the ability of the mechanism to achieve controlled dispensing of oblong ibruprofen test pills.
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The pills were placed at the top of the corkscrew, and a group member would repeatedly try to dispense single pills by turning on the vibrating motor and then shutting it off as soon as a single pill fell. Because visual inspection allowed this person operating the switch to anticipate when pills would fall, they were required to look away from the device and only turn off the motor in response to hearing a pill hit the counter-top below the testing rig. At each of four different motor voltage levels, about 50 pills were dispensed in this manner, and ratios of pill dispensing errors to total pills dispensed were tabulated. An error was counted for every pill besides the first that fell before the motor operator was able to shut off the vibration. The data is shown in Figure 21. Motor power was assumed to be linearly proportional to the square of the voltage drop across the DC motor terminals based on a formula given in2 “Jamming” events, in which pills remained trapped at the top of the corkscrew despite the presence of vibration, occurred sporadically (data not shown). Manual agitation of the pills with fingers was used to break up jams. As would be expected, the error rate decreases as the motor voltage decreases. However, even at the lowest motor power at which any dispensing was observed, the error rate is still about equal to 0.3, far above what would be acceptable for a functional device.
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| Figure 10: Errors/pills dispensed as a function of vibratory motor voltage |
During consideration of the testing results for the two modes of operating the corkscrew described (rotating the corkscrew with the container at an incline, and using vibration alone with the container inverted), it was realized that a third method of operation existed which might work better than the former two. In this method, the container is kept inverted, but before it is vibrated, the corkscrew is rotated such that the end of the pill track is not over the sector-shaped hole in the container cap. Vibration is then applied until one pill has reached the bottom of the track and lies almost completely on the internal surface of what would be the “cap” in an actualy prescription container.
Once this has occurred, the corkscrew is rotated in the direction that makes the threads appear to move away from the container cap (this direction of rotation is preferred since it avoids the problem of pills becoming jammed between the container cap and the corkscrew threads). The corkscrew rotation eventually moves the pill at the bottom of the track over the sector-shaped container opening, allowing the pill to drop out, and finally the corkscrew is rotated in the opposite direction to cut off the container opening from pills that were lined up behind the one that was dispensed.
This is conceptually identical to the method for dispensing pills believed to be described in the pill dispenser patent text authored by Mehrens et. al., in which a “trap door” is opened at the end of the helical pill track to release a single pill1. This method may yield well-controlled dispensing because even though pills are stacked in single file in the corkscrew pill track, the track can be made to be very shallow and have a rough surface1. These two pill track properties may prevent pills from advancing down the track in the absence of vibration, so that only the pill resting on the interior of the “cap” surface is able to fall when the corkscrew is turned to place this pill over the sector-shaped cap hole1.
Unfortunately, our initial tests of this third mode of operation did not easily yield controlled dispensing. However, we believe part of the reason for this is that our current testing apparatus does not allow us to turn the corkscrew any slower than a particular “threshold speed” due to friction between the corkscrew insert and its plastic container. It seems possible that because this threshold speed is higher than necessary, the resultant deceleration of the corkscrew insert to a stop from the threshold speed might be adequate in magnitude to cause pills behind the one meant to be dispensed to move along the pill track and out of the container. To satisfactorily test this third corkscrew operating mechanism, the testing apparatus will need to modified in a way that allows slower movement of the corkscrew insert, perhaps by the application of lubricant or the grinding-down of the corkscrew insert surfaces contacting the plastic container walls.
Conclusions from Corkscrew Design Testing:
The group testing indicated that the Corkscrew Design in general aided dispensing by forcing pills to line up in single file1. However, the testing conducted thus far has not conclusively confirmed that the design allows reliable dispensing of a single pill at a time. Observations suggest that, with the Corkscrew Design, just as with the Gate Design, pills can become stacked on top of each other. The fact that gravity is used to move pills out of the Corkscrew Design container means that this stacking can naturally lead to undesired excess pill dispensing. It was considered worthwhile to investigate other pill dispensing mechanisms that might better address the problem of pill stacking.
Roller Design Concept:
After testing the corkscrew design it became apparent that relying on gravity to remove pills from the containers was responsible for much of the control difficulties with the Gated and Corkscrew Designs. We sought a to improve our design by using a a moving part to more directly provide the pill ejection force. The next design revision carried over the pill track concept, for the purpose of organizing pills in single file. An end the track with a mechanically resistive “door” was added which would not allow pills to exit their container unless actively pushed in the horizontal direction (that is, normal to the gravitational force) by a rotating wheel. A model of the disposable bottle insert used in the implementation of the “Roller Design” is shown in Figure 11.
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| Figure 11: Model of prescription bottle insert used in implementation of the Roller Design |
Figure 12 shows the relationship between the insert and the cap of a bottle when properly assembled, with the bottom of insert flush with the cap. The cap itself has a suitably large sector-shaped hole to allow dispensing.
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| Figure 12: Conceptual illustration of how the insert of the Roller Design would be assembled with a prescription bottle |
To dispense pills, a bottle would need to be inserted into a suitable holder that would place the rotating wheel that ejects pills in the proper position relative to the bottle, as depicted in Figure 13. Like in the design put forward by Mehrens et. al., vibration without rotation of the corkscrew would be used to guide pills down the track 6. The vibration of the bottle and rotation of the wheel could either be done simultaneously or in alternation, and of course both would be ceased upon detection of a dispensed pill falling from the container with an optical sensor. Perhaps two of the biggest open questions regarding the design were how large the rotating wheel should be, and where it should be positioned. It was believed answering these questions would require the tweaking of a prototype implementation of the design.
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| Figure 13: Conceptual illustration of Roller Design Bottle mounted in a holder (as it would be in the home dispensing device). The rotating wheel that would pull out pills is attached to the holder |
Roller Design Implementation:
Because of the complexity of the Roller Design, the group required significant external assistance to get a working prototype put together. The industry mentor was able to make a plastic insert nearly identical to that in Figure 11, likely employing a 3-D printer in the process. In addition, the mentor fashioned a suitable plastic container in which to place the insert much like those they had produced for the Corkscrew and Gate Designs. The need to precisely position the wheel that pulls pills out of the container convinced the group that outside machining assistance would be needed to construct a suitable testing rig. A simple model of what the group envisioned the testing rig would like is shown in Figure 14.
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| Figure 14: Model of desired testing rig for the Roller Design |
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| Here the tested dispensing device can be seen. The rubberized wheel uses surface friction to slowly progress pills down the shoot. |
Roller Design Testing:
PUT INFORMATION ABOUT TESTING HEREPhotodetector: A method for detecting when a pill has dropped:
There is a need to know when to stop driving the dispensing motor. This should be done only after a pill has fallen, but before another falls. We intended to detect the release of a pill by its interference through a beam of light. A bright LED will be lit, as the pill drops through the LED’s light path a photodiode will drop its output voltage in response to the lower light intensity. This will be interpreted as a successful dispensing and the motor will be disengaged. Many colors of LED light could be used, for cost effectiveness IR light will be used for both the transmitting LED and receiver. IR photodiodes are commonly used for communication technologies and are cheaper that visible spectrum detectors as a result of their mass production. The light trip assembly might look like this.
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| _ Here the light trip assembly can been seen. It works on the principal that as a pill falls through it, it will obstruct the path between the LED and photodetector lowering the output voltage of the photodetector in the process._ |
1 Rigor, Herbert W. U.S. Patent 3 480 182, 1969.
fn2. “Motor Formulas”. Electricians’ Toolbox Etc…Information excerpted from Electrical motor Controls by Rockis & Mazur. <http://www.elec-toolbox.com/Formulas/Motor/mtrform.htm>.
Proposed solutions for Pill Cutting Mechanism)
Bowl Design Concept:
The bowl design works on the premise that using an oblong shaped bowl with a vibration source will shake the pill into alignment. The pill travels down a chute and across a retractable ramp. The purpose of this ramp is so that the pill can be gently led directly to the bowl, minimizing large deviations from the intended path. After the medication falls into said “bowl”, the ramp is retracted to allow room for the blade and movement of the bowl. Applying mechanical vibration to the oblong bowl in a specified amount of time aligns the pill per the long axis. When allotted vibration time is complete, a blade with a sheath would then drop onto the pill, splitting it into two halves. The purpose of the sheath is to prevent the halves from being ejected from the bowl as a result of the blade force. The bowl would then move apart, dropping the pill halves into their respective chutes for storage and dispensing.
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| Figure 27: Conceptual Illustration of Bowl Pill Cutter Design. (A)-Pill stop. (B)-Cutting Blade. ©-Movable Bowl Pieces |
Implementation Concerns:
Even though the design adequately addressed the issues of pill alignment using a vibration source, there were still issues of repeatability. The aligning of the pill or tablet with the shape of the bowl is highly variable in that the pill is too free to move about. Deviations in pill alignment could result from anything as little as the user bumping into the machine after initial vibratory alignment. Aside from that, a pill traveling down the chute could potentially bounce out of the bowl, as it is very shallow. Although an angle of descent could be determined to minimize travel velocity for a specific pill, the criteria of the cutter states that it must accept pills of different shapes and sizes. Whereas a declination angle could be determined for one pill, another pill of larger size and weight could travel faster due to lower frictional resistance. There is also the concern of medication rigidity after the blade is dropped onto the pill. Without the pill being held rigidly in place, there are many unknowns as to how the blade forces will affect the pills position at the time of impact.
Implementation:
The downfalls of the initial cutting design led to further device specification to more thoroughly address issues in pill positioning. First, an alignment mechanism must be derived that will continually align dispensed medication in a specific and repeatable manner. Simply put, dispensed pills must fall to the cutting mechanism in the same way despite their size and shape. Secondly, the pill must be rigidly held in place before and during cutting to minimize large variations in pill location. Taking the new specifications into consideration, an entirely new design was thought up.
Clamp Design Concept:
The basic principles of the clamp design are that the cutting mechanism should utilize the geometrical properties of a “V” shape and rigid clamping to position a pill. In utilization of a v-shaped chute, elongated tablets will naturally line up parallel to the groove and round pills will slide down parallel to one wall of the “V”.
First Iteration
The first iteration of the clamp design utilized the V-shaped chute for consistent pill alignment. Clamps (Figure 13B) where used to both stop and align the pill as it fell through the chute. Side clamps (Figure 13C) would then squeeze the pill to ensure accurate placement in the center of the chute and then clamps B would center the pill with respect to the blade. After the blade effectively cut the pill, clamps B would move and the halved pill would proceed to its respective place for storage or dispensing.
The issues of pill rigidity where thoroughly addressed with the implementation of moving clamps, however this design also brought up an issue with the angle at which the clamps squeeze the pill. Because the pill is at a 45 degree angle with respect to the end clamps (clamp B) there was the possibility that the pill could be torqued up into a vertical position. In that case, the blade would be cutting the pill along its longest axis where the intent is to split the pill along its shorter axis (from the top). This design was also very conceptual, therefore real life mechanics of clamp movement where not considered and parts in the proposed model moved along awkward planes at many different angles.
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| Figure 27: Initial concept model for Ramp Pill Cutter Design. (A)-A pill to be cut. (B)- Length pill clamps. ©- Side Pill Clamps. (D)-Cutting Blade |
Second Iteration
In the second iteration, both the V-shaped chute and clamp designs were taken but moved to work the pill along different planes. A pill would travel down the chute aligned within the groove of the chute. Slits coming through the underside of the chute would allow pins to rise, effectively stopping the pills travel. The side clamps would then clamp the pill from the sides ensuring that it is held in the center with respect to the chute. Another pin would be raised from behind the pill. Shortly after, the two pins would move closer together until resistance is felt, in which case the pins would stop and the pill would be centered with respect to an over hanging blade.
Issues with conventional mechanics and the movement of clamps was solved in that all the parts could be moved along horizontal and vertical axis, however the pill was still unrestricted in the upward direction. After cutting, the possibility of halves being ejected upward was still a relevant.
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| Figure 28: Second conceptual model for a Clamped Pill Cutter Design. (A)- Pin slots. (B)- Side pill clamps. |
Final Iteration
In order to finally solve the pill clamping issues of effectively holding the pill in place during all steps of the cutting process, it was realized that having a part drop from the top would efficiently wedge the pill in the groove of the chute, covering the pill from all sides. This clamp design for the cutting mechanism consists of four main components: a stopper, a pressure plate, guiding pins, and the blade. Once a pill is released from the pill selecting mechanism, it falls via gravity down the v-shaped chute. A stopper in the lowered position at the end of the chute stops the pill from sliding. A pressure plate positioned above the end of the chute is then lowered on top of the pill, clamping it down against the walls and acute angle of the chute. Guiding pins rise through thin slits on the underside of the channel and push the pill into a centered position with respect to the blade. Lastly, a guillotine style blade is quickly released, traveling through an opening in the middle of the pressure plate and through the pill, splitting the pill in two halves. Pressure plate, stopper and guiding pins are retracted and the two halves are free to slide to their respective chutes for storage or dispensing.
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| Figure 29: Conceptual model for V-Clamp Pill Cutter Design. (A)-V-Shaped Chute. (B)- Pill Stopper. ©- Pressure plate. (D)-Guide pin slit. (E)- Pill cutting blade |
Clamp Design Implementation:
Implementation of the stopper at the end of the chute was required for control of the pill. The pressure plate utilizes the same clamping mechanism but combined with the v-shaped chute, allows for uniform pressure around the entire pill. The sequence of execution of each component is also important. Clamping of the pill must occur before centering of the pill because there is a possibility that the centering could “tweak” the pill off axis and out of longitudinal alignment.
In deriving a prototype, Delrin was used due to its low friction surface properties. This slick surface allows for easy manipulation of pills by the pins after they have been clamped. At also contributes to low mechanical wear and provides for a strong, sturdy structure. Also defined in the final prototype was the size of the blade. Conceptual models illustrate a large blade capable of covering the entire width of the pill, however final implementation utilizes a small blade less than 5 mm in width. The blades were made by X-Acto and are readily available in retail hardware stores. Implementation of X-Acto’s product was quick and easy because this specific blade came attached with a plastic shaft that the prototype utilized as a mounting point. The same mounting point can be used with future implementations of a solenoid or spring driven source of force. Lastly, springs were utilized in the mechanism for lowering the pressure plate. Ideally, as a solenoid drives the pressure plate down, the springs act as a buffer to ensure that too much force is not applied to the pill. The maximum amount of force applied to the pill is not determined by the power of the motor but rather the spring constant. The two metal dowels to the sides of the springed dowels act as guiding rods for the pressure plate.
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| Figure 30: Actual prototype of V-Clamp Pill Cutter Design produced by Brad Sargent of Omnica Corp. |
Clamp Design Limitation Specifications:
The upper limitation on acceptable pill size is determined by the distance between the guiding pins and the size of acceptable girth between the groove of the chute and the pressure plate. The largest pill acceptable is 23 mm in length with a thickness of 15 mm. The smallest pill acceptable is 5 mm in length with a thickness of 4 mm.
Clamp Design Testing:
Preliminary testing utilized the manual movement of parts and eye-coordination to align the pills. Trails have shown that the V-shaped chute consistently delivers an aligned pill each time medication is dispensed. Also, the current spring is sufficient in rigidly holding the pill without causing any structural damage and when combined with the low friction of Delrin, pills are easily maneuverable while being clamped. In testing the actual splitting of the pill, manual force was applied to the spring/pressure plate mechanism and the blade was driven by manual hammering of the blade through the pill. Results show that pills are cut accurately in half given that enough velocity and force is applied on the first stroke. At slower velocities and forces, the pill tended to fracture off the plane of intended splitting. There was also a concert that the short width of the blade would not be sufficient, however the pill still breaks in a strait line given enough force and velocity due to the brittle nature of the pill. Future tests will utilize weights of known mass dropped at predetermined heights so that an appropriate force driver can be made for consistent cutting.
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| Figure 31: Actual outcome of V-Clamp Pill Cutter Design on Aspirin tablet. |
Conclusions from Clamp Design Testing:
Preliminary tests show that the clamp cutting design does exactly as it was designed to do and it serves as a very plausible design for integration into the final device. One problem realized in the mechanical cutting of medication is the prevalence of pill fragments. These fragments raise contamination issues as we do not want different medication fragments mixing together in the chance that these might be accidentally ingested by the user. Therefore, further methods of cutting might have to be sought or the implementation of a self cleaning mechanism might need to be designed.
Design of the Pill Reservoir:
If the user chooses to fraction a pill, where will the remaining piece be stored? This was one of the last things we tried to answer. The first design that came to mind was a sedentary container. The reservoir had no moving parts, it was assumed that a network of chutes would orchestrate which column the pill half would fall into.
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| The earliest version of the reservoir did not have moving parts, rather it relied on external routing methods to orchestrate which container is accessed. |
Very quickly it was realized that this is a sub-optimal method of storing pill halves. First, for this to be implemented a very complex network of chutes would have to be developed that bring the pill from the cutter to the reservoir. Second, there is no clear way of selecting a pill half for dispensing if the user so chooses. Based on this, a second design was rendered that did not require complex chutes. Essentially the pill fractions are held within a rotating propeller. If a pill half should be dispensed, the half of interest is centered over a release plate which opens and dispenses the medication.
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| The second version of the reservoir was based off a propeller. The propeller rotates to bring the compartment of interest over the dispensing door. |
Our industry mentor suggested that the design should be modified to lie on its side. This will allow gravity to act on all pieces evenly and improve the consistency of motor speed through each turn cycle. We settled on a sphere shape which would have a natural curvature, forcing the pills to the center towards the ejection port.
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| The third version of the reservoir used a sphere shape compartment to force the pills towards the center of the compartment. |
After realizing that it will be very hard to actuate both of the bottom pieces it was determined that the edges of the sphere should have gear teeth. This will allow us to mechanically interact with the assembly. Unfortunately our team did not have enough time to fabricate a prototype of this component. We did however Solidworks model it with exact proportions to asses its feasibility.
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| A final Solidworks rendering of what the pill reservoir might look like |