7 research outputs found
Needle-free injection into skin and soft matter with highly focused microjets
The development of needle-free drug injection systems is of great importance
to global healthcare. However, in spite of its great potential and research
history over many decades, these systems are not commonly used. One of the main
problems is that existing methods use diffusive jets, which result in scattered
penetration and severe deceleration of the jets, causing frequent pain and
insufficient penetration. Another longstanding challenge is the development of
accurate small volume injections. In this paper we employ a novel method of
needle-free drug injection, using highly-focused high speed microjets, which
aims to solve these challenges. We experimentally demonstrate that these unique
jets are able to penetrate human skin: the focused nature of these microjets
creates an injection spot smaller than a mosquito's proboscis and guarantees a
high percentage of the liquid being injected. The liquid substances can be
delivered to a much larger depth than conventional methods, and create a
well-controlled dispersion pattern. Thanks to the excellent controllability of
the microjet, small volume injections become feasible. Furthermore, the
penetration dynamics is studied through experiments performed on gelatin
mixtures (human soft tissue equivalent) and human skin, agreeing well with a
viscous stress model which we develop. This model predicts the depth of the
penetration into both human skin and soft tissue. The results presented here
take needle-free injections a step closer to widespread use
Highly focused supersonic microjets
The paper describes the production of thin, focused microjets with velocities
up to 850 m/s by the rapid vaporization of a small mass of liquid in an open
liquid-filled capillary. The vaporization is caused by the absorption of a
low-energy laser pulse. A likely explanation of the observed phenomenon is
based on the impingement of the shock wave caused by the nearly-instantaneous
vaporization on the free surface of the liquid. An experimental study of the
dependence of the jet velocity on several parameters is conducted, and a
semi-empirical relation for its prediction is developed. The coherence of the
jets, their high velocity and good reproducibility and controllability are
unique features of the system described. A possible application is to the
development of needle-free drug injection systems which are of great importance
for global health care.Comment: 10 pages, 11figure
Highly focused supersonic microjets
The paper describes the production of thin, focused microjets with velocities
up to 850 m/s by the rapid vaporization of a small mass of liquid in an open
liquid-filled capillary. The vaporization is caused by the absorption of a
low-energy laser pulse. A likely explanation of the observed phenomenon is
based on the impingement of the shock wave caused by the nearly-instantaneous
vaporization on the free surface of the liquid. An experimental study of the
dependence of the jet velocity on several parameters is conducted, and a
semi-empirical relation for its prediction is developed. The coherence of the
jets, their high velocity and good reproducibility and controllability are
unique features of the system described. A possible application is to the
development of needle-free drug injection systems which are of great importance
for global health care.Comment: 10 pages, 11figure
Highly focused supersonic microjets: numerical simulations
By focusing a laser pulse inside a capillary partially filled with liquid, a vapour bubble is created that emits a pressure wave. This pressure wave travels through the liquid and creates a fast, focused axisymmetric microjet when it is reflected at the meniscus. We numerically investigate the formation of this microjet using axisymmetric boundary integral simulations, where we model the pressure wave as a pressure pulse applied on the bubble. We find a good agreement between the simulations and experimental results in terms of the time evolution of the jet and on all parameters that can be compared directly. We present a simple analytical model that accurately predicts the velocity of the jet after the pressure pulse and its maximum velocit
Highly focused supersonic microjets: numerical simulations
By focusing a laser pulse inside a capillary partially filled with liquid, a vapour bubble is created which emits a pressure wave. This pressure wave travels through the liquid and creates a fast, focused axisymmetric microjet when it is reflected at the meniscus. We numerically investigate the formation of this microjet using axisymmetric boundaryintegral simulations, where we model the pressure wave as a pressure pulse applied on the bubble. We find a good agreement between the simulations and experimental results in terms of the time evolution of the jet and on all parameters that can be compared directly. We present a simple analytical model that accurately predicts the velocity of the jet after the pressure pulse and its maximum velocity
Coordinated emergency control of load shedding and FACTS devices
This paper describes the development of a control system and control strategies capable of governing multiple flexible AC transmission system (FACTS) devices in coordination with load shedding. The main purpose of the presented coordinated control system is to remove overloads caused by lines' outages in transmission network. The proposed control system is based on linearized expressions in steady state. Therefore they do not require intensive computations. A simulation model of the control system is suitable for real time implementation. It constantly monitors power flows and generates appropriate control signals to each load and FACTS device in order to maintain acceptable power flow levels. It has been interfaced with load flow software to test its effectiveness through non-linear simulations using the 14 bus IEEE test power system as the study case. The results obtained are presented