PRESENTED BY:
Miss Abina Aliyar

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MICROFABRICATED DEVICES FOR CONTROLLED BIOCHEMICAL RELEASE
INTRODUCTION
 Here we will be discussing about the controlled release for both drug delivery and other biological applications.
 Controlled release refers to the process in which an appropriate amount of drug or biochemical agent is released from a drug-encapsulating device to the target as a function of time, stimuli or physiological conditions.
 First, biochemical release systems based on micro fabricated devices are reviewed.
 Secondly, a novel concept for controlled release-discrete chemical release is introduced.
 Thirdly , adaptive release systems are discussed as a future direction for controlled chemical release.
LITERATURE SURVEY
 In traditional drug delivery, common delivery routes include oral, pulmonary, transdermal and injection, and they each have certain advantages and disadvantages associated with them.
 All of these routes, except for direct injection into a vein or muscle tissue, have cellular layers that are encountered, which function as a barrier to transport into the systemic circulation.
 To avoid this, controlled release is used to achieve sustained or pulsatile drug release.
 Sustained release is used to achieve a constant release of a drug over an extended period of time.
 Later on adaptive release systems have been introduced as a future direction for controlled chemical release.
MICROFABRICATED DEVICES
 Micro device based systems can provide more flexible temporal and spatial control over the drug release process.
 For most of the micro fabricated devices, the chemical delivery methods employed can be categorized into two groups:
1. Passive release-by preset diffusion rate.
2. Active devices-by real-time control of external or internal release regulator
1.PASSIVE DEVICES
 Drug released by pure diffusion.
 No internal, external or osmotic pressure is applied.
 Don't require the application of stimulus.
 Drug release rate is preset by carrier design.
Working of Polymeric microchip
 This would be advantageous for long-term treatment of conditions requiring pulsatile drug release.
 The main body of the device is composed of a reservoir containing substrate that is fabricated from a degradable polymer.
 drug-containing reservoirs are covered with degradable membranes.
 Chemicals from the reservoirs can be released at different times on the basis of the characteristics of the reservoir membranes that affect their degradation rate.
 By varying the size and polymer composition of the microchip, the number and volume of the reservoirs, and the composition of the membranes, these devices could offer the opportunity to tailor specific release times of chemicals.
 This enabling the construction of complex release profiles that provide both pulsatile and continuous release of different drugs or chemicals.
2.ACTIVE DEVICES
 The release of drug from active devices is not purely by diffusion but by controllable pressure.
 Application of stimulus is required.
 Active microchips could provide more flexibility for the drug administration or control of release rate.