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International Journal of Bioprinting 3D printing and 3D-printed electronics in smart drug delivery devices

1.1. Smart drug delivery devices be used [16,17] . When exposed to such stimuli, these “smart”
Smart drug delivery devices are a type of drug delivery materials would undergo changes to their properties such
devices which can trigger the release of drugs as needed as phase, solubility, or shape. These property changes can
from the device. These devices can control when the start then be used to control or trigger the release of drugs
and end of the drug release from the device is, allowing for when the “smart” material is exposed to the necessary
the drug release to be turned “on” and “off” as needed. Thus, stimuli. The drug intended for delivery could be directly
the duration, the rate, as well as the location of the drug loaded into the “smart” materials for release or the “smart”
release can be controlled. This improves the control over material can function as a controlling mechanism to
the concentration of drugs within the patient, increasing control the release of drugs stored in a drug reservoir .
[18]
the effectiveness of the drug therapy and decreasing the For non-physiological stimuli-triggered “smart” materials,
possibility of adverse side effects . There are mainly two an external interference or source would be needed
[5]
categories to classify smart drug delivery devices. These to trigger the drug release. However, for physiological
two categories are as follows. stimuli-triggered “smart” materials, the drug release can be
self-regulated by changes in the physiological conditions of
The first category is smart drug delivery devices with [19]
a “passive” triggering of drug release from the device. For the patient or in the surrounding area of the material .
these “passive” devices, the trigger of the drug release
from the device requires an external stimulus. External 1.2. Addition of electronics to smart drug delivery
stimuli such as infrared light (IR), ultraviolet light (UV), devices
ultrasound, magnetic field, or heat can be used [6-9] . Besides For the “active” category of the smart drug delivery devices,
these external stimuli, a microchip can also be used to electronics can be added for use as both the monitoring
trigger the drug release. The microchip allows for either and triggering components of the device. Doing so would
the manual or wireless control of the drug release by the increase the areas of application of the devices and would
[10]
doctor and nurse or by the patient . For this type of smart also confer several advantages to the devices. The addition
drug delivery device, while it allows for the control of drug of electronics and sensors to the smart drug delivery device
release, it requires an external source to trigger the drug would allow for the patient’s wound or medical condition
release. Without any external interference, drug release to be monitored. This could be done by tracking the
would not be triggered by the device. certain physiological conditions such as pH, temperature,
or the amount of various biomarkers of the patient or in
The second category of smart drug delivery devices is the surrounding area. The information on the patient’s
“active” smart drug delivery devices. Drug release from condition can then be directly sent to the healthcare
“active” smart drug delivery devices does not require an professional taking care of the patient or to the patients
external stimulus or external interference. Instead, changes themselves. This allows for the healthcare professional to
in the physiological conditions of the patient or in the have more information on the patient’s condition and to
surrounding area of the device can cause the triggering of provide better care for the patient . It would also allow
[20]
the drug release. One way that the physiological condition for the patients to keep track of their own physiological
changes can be used to trigger the drug release is through information which could help the patients better monitor
the use of electronic sensors. The sensors can detect these their own conditions . The electronics which are added to
[21]
physiological changes and control the drug release through the devices can also be used to control the drug release. This
a microchip . “Smart” materials can also be used to detect can be done either through information from the sensors or
[11]
changes in physiological conditions and trigger drug directly by the healthcare professional or patient . Using
[22]
release . For the “active” smart drug delivery devices, sensors to monitor the condition of the patient and supply
[12]
the drug release can be triggered and controlled in a self- the necessary dose of drug as needed would also increase
regulated, closed loop system. These devices can detect the compliance of the patient. This is especially applicable
changes in the patient or in the surrounding area of the for illness which requires multiple drug doses daily such as
device and trigger the drug release as needed without any diabetes . The electronics can also control the start and
[23]
external interference . end of drug release, controlling the timing, duration, and
[13]
“Smart” materials are materials which undergo a phase amount of drug released. This would allow for the precise
or property change when subjected to certain stimulus. For control over the amount of drugs which enter a patient’s
[24]
the purpose of drug delivery, these could be physiological circulatory system so as to reduce possible side effects .
stimuli such as changes in body temperature, pH, enzymes, The focus of this review paper is on the smart drug
or biomarkers [14,15] . Other non-physiological stimuli such delivery devices which have electronics. The review paper
as ultrasound, magnetic fields, IR, and UV lights could also will cover the use of 3D printing for smart drug delivery

Volume 9 Issue 4 (2023) 145 https://doi.org/10.18063/ijb.725