Final Design

 Figure 1: Final Design of Pillsafe for Demo                                             Figure 2 : Top View of Final Design of Pillsafe for Demo

     The Pillsafe unit has to be compact, interactive, able to detect pill dispensation and utilize blister packs. Those issues were each addressed and discussed in the following sections.Size

The design needs to be relatively compact or it will not be appealing enough for users to want to carry it around with them.  The general consensus between the team members and the sponsors was that a case design roughly around the size of a typical smart phone would be acceptable. The dimensions decided on are 5.85 x 11.43 x 1.01 cm (2.3 x 4.5 x 0.4 inches).

Interactivity

            The device needs to have wireless communication capabilities in order to transmit (in real-time) data associated with pill dispensing. For this design, an essential method of interactivity in the design will be the wireless communication between the device and the user.

A separate electrical engineering team from UCSD has been simultaneously working on the wireless communication process for the Pillsafe. They are interfacing an Arduino Uno with a SM5100B Global Systems for Mobile Communications/General Packet Radio Service (GSM/GPRS) Cellular Shield (see Figure 3 ) which enables the use of 2G and 3G cellular communication. The SM5100B has a T-Mobile SIM card in it to allow for text messaging. This enables interactions between the Pillsafe unit and cellphone via text messages allowing for reminders and setting changes to be conveniently made through a cellphone.

                                                                                                                         Figure 3: SM5100B Cellular Shield

 The design will also need some method of alerting the user at certain times. Indicators will alert Pillsafe carriers of events such as the scheduled pill taking time and low battery. 2 LEDS, 1 red and 1 green will indicate different modes 

Table 1: LED states and their corresponding meaning

            Aside from alerting the user through use of text messages, there will also be two other more direct methods of alerting them of events. Similar to a cell phone there will be an audible alarm that can be programmed with different personalized melodies. The other method is a vibrate mode for more discrete use. A piezo buzzer will be used for the audible alarm and micro vibrating motor for the vibrating alarm.   

Blister Pack

            One essential aspect of the Pillsafe user experience is how the pills are dispensed. The team initially looked at designs which had a mechanism that dispensed the pills for the users. It was decided that as blister packs are in wide use and are familiar to the general public, it would be satisfactory to expect patients to puncture blister packs by hand.

The industry standard for blister packs is rigid PVC. (Pilchik) Rigid PVC is cheap, easy to form, and provides a sufficient barrier from moisture. If more moisture protection is required, other layers can be added to the PVC. Depending on the shape, number and size of pills wanted, different pills can be made using different blister pack molds (see Figure 4).

Figure 4: Examples of Different Sized Blister Packs

Indication of Pill Dispensation

Different methods were considered and it was decided that optical sensors set in a grid corresponding to pill locations was the simplest and most reliable choice (see Figure 5). The sensors are reflective object sensors that have IR emitters and detectors. Different objects being in the proximity of the sensor resulted in different amounts of light being absorbed and reflected. The sensors returned different readings for a full blister, an empty blister and the space between blisters.

Using a microcontroller, the Pillsafe will turn on the sensors when the blister pack is fully inserted in the case. Each sensor will take a reading and indicate whether a pill is present in the corresponding blister or not. This data will then be compared to previous readings and compared to check if pills were dispensed.   

Figure 5: Optical Sensor Grid on Protoboard with Gum Blister Pack