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  • Iontophoresis Implementation Using Microchip Microcontroller

  • Created: Sep 03, 2014

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Iontophoresis is a process used to deliver drugs through the skin into the body. A transdermal drug is a charged compound driven through the skin by the flow of electrical current. To deliver the correct dosage, the current flow through the skin must be actively controlled. This can be performed by means of an automated system.

Iontophoresis is the method of using an electrical current to assist the infusion of a drug through the skin. The advantages to this approach are many. First, the medicine can be dosed at very high levels locally, rather than a lower dose distributed throughout the body. Second, there are far fewer side effects associated with localized application of the medicine. At very high levels, the efficacy of the medication can be greatly improved. In order to accomplish this, a specially formulated medicine is prepared, which bonds to the electrons and is moved by current through the skin. Historically, this has required significant electronics and a trained operator to monitor the current and the necessary safety features to protect the patient. However, with recent advances in technology, switched mode power supply design, and cost-effective, high-performance microcontrollers, the production of low-cost or single-use dispensers for these drugs has become possible. This proof of concept design uses a low-cost, 8-bit PIC12F683 microcontroller with mixed signal features and some off-the-shelf components.

In this circuit, Q1 is the main switching transistor. The MOSFET VDS breakdown and the breakdown voltage of D1 should be greater than the maximum desired voltage output of the circuit. When the microcontroller detects that the output current has dropped below the required level, it pulses the MOSFET four times in rapid succession to boost the voltage output. The PIC12F683 was selected as the microcontroller for the device because of its small size, low-cost, internal analog-to-digital converter, fixed voltage reference, integrated comparator, PWM, hardware timer, and internal EEPROM. The design also includes two LEDs for the user interface. There is a start button, which is connected to the Reset of the part.



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