• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.837-841
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• 2008

Propulsion of gene coated micro-particles is desired for non-intrusive drug delivery inside biological tissue. This has been achieved by the development of a device that uses high power laser pulses. The present paper looks at the mechanisms of micro-particle acceleration. Initially, a high power laser pulse is focused onto the front side of a thin aluminium foil leading to its ablation. The ablation front drives a compression wave inside the foil, thus leading to the formation of a shock wave, which will later reflect from the rear side of the foil, due to acoustic impedance mismatch. The reflected wave will induce an opposite motion of the foil, characterized by a very high speed, of the order of several millimeters per microsecond. Micro-particles, which are deposited on the rear side of the foil, thus get accelerated and ejected as micro-projectiles and are able to penetrate several hundreds of micrometers inside tissue-like material. These processes have been observed experimentally by using high-speed shadowgraphy and considered analytically.

• International Journal of Precision Engineering and Manufacturing
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• 제9권3호
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• pp.68-71
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• 2008

Transdermal and topical drug delivery with minimal tissue damage has been an area of vigorous research for a number of years. Our research team has initiated the development of an effective method for delivering drug particles across the skin (transdermal) for systemic circulation, and to localized (topical) areas. The device consists of a micro particle acceleration system based on laser ablation that can be integrated with endoscopic surgical techniques. A layer of micro particles is deposited on the surface of a thin metal foil. The rear side of the foil is irradiated with a laser beam, which generates a shockwave that travels through the foil. When the shockwave reaches the end of the foil, it is reflected as an expansion wave and causes instantaneous deformation of the foil in the opposite direction. Due to this sudden deformation, the microparticles are ejected from the foil at very high speeds, and therefore have sufficient momentum to penetrate soft body tissues. We have demonstrated this by successfully delivering cobalt particles $3\;{\mu}m$ in diameter into gelatin models that represent soft tissue with remarkable penetration depth.

• 한국항공우주학회지
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• 제36권6호
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• pp.587-593
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• 2008

본 연구의 목적은 신체 조직의 손상을 최소화할 수 있는 경피(transdermal) 및 국부적인(topical) 약물전달을 가능하게 하는 마이크로 입자가속시스템 개발에 있다. Ballistic 역학을 기반으로 하는 본 방법을 통하여 체순환을 위한 경피 및 국부적 약물 전달이 가능하다. 얇은 금속 포일의 한 쪽 면에 마이크로 입자들을 얹어놓고 뒷면에 레이저를 조사하면 충격파가 발생하고, 이 충격파는 포일을 통과하며 포일의 끝에서 금속-공기간의 acoustic impedance 차이로 expansion wave로 반사되어 포일이 반대 방향으로 변형을 일으키게 한다. 이 순간적인 변형으로 인해 포일에 붙어있던 마이크로 입자들이 가속되어 튕겨 나가게 된다. 입자들이 가속되는 속도가 굉장히 크기 때문에 이들은 신체 조직을 침투할 만한 충분한 운동량을 갖고 있다. 입자들의 침투 여부를 확인하기 위해 우리는 5${\mu}m$ 크기의 코발트 입자들을 연조직을 묘사하는 젤라틴에 가속시켰으며, 주목할 만한 침투 깊이를 얻으며 실험에 성공하였다.