# A Review of Medication Adherence Monitoring Technologies +
## 4 A Review of Medication Adherence Monitoring Systems
### Proximity Sensing  
The visionary concept of IoT relays on some technologies, among which is the proximity detection [129; 130]. Hence, objects usage in our daily life can be monitored by sensing their proximity to other things. Two important wireless communication technologies that are currently used for proximity detection and sensing are RFID [131] and NFC [132]. Overall, RFID and NFC are contactless short-range communication technologies that can be integrated in everyday life objects to sense the daily activities [133; 134]. Here, we describe the RFID-based and NFC-based systems in medication taking applications and their usefulness and shortcomings. An early demonstration that applied RFID technology for medication taking was designed by [PERSON] et al. [75]. The system uses an RFID tag attached to a pill bottle that is placed on a platform embedding an RFID reader and LEDs. The LEDs flash to notify the patient when it is time to take medication. Using this system, it is inferred that the medication is taken when the medication bottle is picked from the platform and it is not within the coverage radius of the RFID reader anymore. The caregiver can track the patient's adherence via an Ethernet connection with the platform. Another RFID-based prototypical system is SmartDrawer [76]. A drawer with an RFID reader that is capable of inventorying the pill bottles that are stored inside it as well as keeping a record of drug taking activities, is used. The pill bottles are equipped with RFID tags for identification and tracking. The system records the type of bottle and when it is removed from the drawer. In other words, it is assumed that the medication is taken when the bottle of that medicine is removed from the drawer and it is not within the scope of the RFID reader. RMAIS is a system that relies on RFID [77]. It utilizes RFID technology, a scale, an Arduino \(\upmu\)C board, an LCD panel, and a motorized rotation platform. Each pill bottle is equipped with a passive RFID tag that stores the medicine information and is read by a very short range RFID reader that is attached to the scale. Initially, the \(\upmu\)C obtains the medicine details from the RFID tags. Based on the inherited information, the platform notifies the patient about medication taking time and introduces the medicine on time by rotating the platform and pushing the required pill bottle onto the scale. The LCD panel is employed to provide the dosage instructions. Finally, based on the scale measurement, the system can detect if the medication has been consumed. RFID is not the only available tool for this approach. Other short communications-based approaches designed a smart blister that is equipped with a \(\upmu\)C along with the NFC technology available on mobile phones, to develop an adherence tele-monitoring system [78; 135]. The idea is that the smart blister records the event of pill removal and reports this activity to a mobile phone that is in the proximity via NFC. The mobile phone then communicates this event to a remote server to be accessed by the caregiver that assesses the medication intake adherence. As with the previous technology-based systems for medication adherence monitoring, proximity sensing-based systems have advantages as well as limitations. The main advantage is the possibility of retrieving information such as dosage instructions that may include timing, frequency, and quantity. Such information can be helpful when considering elderly patients. Another advantage of using proximity sensing is the non-invasiveness, as sensing tags are usually attached to the pill containers. However, the main limitation of these systems is the requirement that the pill container being located within a short distance (several centimeters) of the vicinity of the main part of the system, which is the reader. In addition, the possibility of encountering unrealistic situations in which it is assumed that the medication is consumed by patient when it is only moved away from the reader.