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Biomedical subjects

A Passian

Publications and source records attributed to A Passian.

6 recordsLinked to original sources
PubMed2003

Thermal transpiration at the microscale: a Crookes cantilever.

Local temperature inhomogeneities in systems containing micron and submicron objects can result in unexpected consequences. If the mean free path of the host gas constituents is comparable to a characteristic length of the system, then a net exchange of momentum occurs between the constituents and the involved surfaces. For a given temperature gradient and a given pressure range, this results in the presence of Knudsen and Knudsen-like forces (KF). The pressure dependence of these forces has been studied using a microelectromechanical system composed of a microcantilever near a substrate surface. Nano-Newton scale KF are observed by the bending of the microcantilever as monitored by the charge variation on the microcantilever-substrate assembly in a capacitive mode.

Journal Article↗
PubMed2001

Telesensor integrated circuits.

Progress in personal computing has recently permitted small research programs to design and simulate application-specific integrated circuits (ASICs). Inexpensive fabrication of silicon chips can then be obtained using chip foundries, and quite complex circuits can be greatly reduced in size with an accompanying increase in certain performance characteristics. Within the past 5 years it has also become possible to design ASICs which can transmit and receive radio signals and which thus may be employed in applications in which wired connections for input and output of signals are not practicable. We are currently developing research-grade prototype ASICs for the monitoring of human vital signs. In this case one or more sensors placed on an ASIC provides a signal to be transmitted a distance of 2-3 meters to a receiver/display unit. The use of ASIC telesensors provides the possibility of wireless monitoring, including long-term monitoring, with inexpensive and unencumbering devices. Their self-contained nature permits a number of potential uses in future biomedical applications as new sensors are devised which are amenable to deployment on silicon.

Arsenicals↗
PubMed1995

The impact of computer implementation on nursing work patterns: study design and preliminary results.

This paper describes a three phase evaluation of nursing work patterns on two University Hospital Giessen medical wards and the influence of introducing electronic data processing into the nursing environment. Results of the first phase are presented. The first phase was a baseline evaluation prior to the introduction of any electronic data processing functions. Work sampling showed that, on average, 15% of a nurse's time was spent providing general nursing care, 35% on special nursing care, and 30% on administrative activities. The remaining 20% was used for activities not directly related to nursing. In addition, a survey was conducted, revealing that about one third of the nursing staff had had contact with computers prior to start of the study. The enthusiastic attitude toward using computers on the ward was striking. Nursing staff expected that their work would be easier after the introduction of computers, that electronic data processing would save time, and that the computers would be easy to use. The staff did not express such positive expectations for the use of bedside terminals or portable devices.

Attitude to Computers↗
PubMedDate not supplied

Manipulation of microcantilever oscillations.

Experimental observation of self-sustaining oscillations via a delayed feedback system is presented for a rectangular silicon microcantilever. The system is modeled as one and two-dimensional damped oscillator and the resulting delay differential equations are studied in frequency and time domain. The shortcomings of each model are outlined, and an improved formulation of the dynamics of the cantilever is presented.

Journal Article↗
PubMedDate not supplied

Observation of Knudsen effect with microcantilevers.

The Knudsen effect is estimated theoretically and observed experimentally using a U-shaped silicon microcantilever. Though Knudsen forces are extremely small in most cases involving microcantilevers, there exist situations where these forces can be significant and may be important in atomic force microscopy and in microelectromechanical systems (MEMS). The criteria for the presence of Knudsen forces are outlined and an analytical expression in the form of a linear function of the pressure is given for the force in the free molecular regime. The experimental results display peaks in the transitional regime while varying linearly in the molecular regime.

Journal Article↗