# A Review of Medication Adherence Monitoring Technologies +
## 4 A Review of Medication Adherence Monitoring Systems
### Sensor-Based Systems
#### 4.1.1 Smart Pill Container  
Pillboxes and pill bottles equipped with sensors have been developed for monitoring the medication-taking activity. In this context, [PERSON] et al. [12; 61] developed MedTracker. It is one of the earliest approaches that uses a 7-day multi-compartment pillbox embedding plungers in each compartment. It was designed to detect the lids of boxes opening as the plungers would activate a switch inside the pillbox that then triggers the micro-controller. The system uses Bluetooth technology for wireless transmission of the data to a nearby computer. Data was transmitted over the Bluetooth link every two hours for the aim of prolonging the lifetime of system, which was using a 9 V battery. The system includes RAM for storing medication taking events when there is no connection with the base station. However, it is obvious that the system is simple and is error prone as it considers any lid opening event as medication taking. Regardless of its simplicity, the system achieved a lifetime of eight weeks only, given it was powered from a considerably big battery.  
In another approach that was recently carried on by [PERSON] et al. [62], PillSense has been proposed. It uses a 3D printed pill bottle equipped with a magnetic switch sensor, an accelerometer, and a load cell. Furthermore, the system uses PIP-Tag more [104] as a platform for collecting the data from the employed sensors and then transmitting them wirelessly to a base station attached to a nearby computer. The system simply relies on the idea of collaborative sensing where the switch sensor is utilized for monitoring cap removal, the accelerometer for monitoring pill pickup event,and the load cell for bottle weight sensing. Hence, with the aim of saving as much energy as possible, PillSense was designed such that it monitors cap removal through the magnetic switch sensor and only activates the accelerometer for motion sampling when cap removal is detected. Upon cap re-closure, the accelerometer is deactivated and the weight sensor is activated for one-time bottle weight sensing. Pill bottle weight checking adds another element of validation to see if there is a difference in the weight, each time the cap is removed. The system is wireless, unobtrusive, and supports portability. More importantly, it is energy efficient as it can work for more than three weeks on a coin-cell battery.  
For a project that intended observing daily living of elderly people, [PERSON] and [PERSON] [63] developed a pillbox similar to that reported in [12; 61]. A 7-day compartment has been equipped with a Microcontroller (MCU), a ZigBee wireless module, an accelerometer, and a battery. Data were transmitted to a laptop located in the patient's home for further processing. The system has been clinically tested over a duration of ten months with two participants, but no results about the performance were reported.  
It can be seen that such an approach aims to eliminate the intervention and attachment of sensors to the human body, and by that it ensures user's comfort while maintaining accuracy by using the accelerometer sensor. However, the system does not ascertain if a pill is actually ingested or not by the user.