6R instrumented spatial linkages for anatomical joint motion measurement--Part 2: Calibration.

The six-revolute-joint instrumented spatial linkage (6R ISL) is often the measurement system of choice for monitoring motion of anatomical joints. However, due to tolerances of the linkage parameters, the system may not be as accurate as desired. A calibration algorithm and associated calibration device have been developed to refine the initial measurements of the ISL's mechanical and electrical parameters so that the measurement of six-degree-of-freedom motion will be most accurate within the workspace of the anatomical joint. The algorithm adjusts the magnitudes of selected linkage parameters to reduce the squared differences between the six known and calculated anatomical position parameters at all the calibration positions. Weighting is permitted so as to obtain a linkage parameter set that is specialized for measuring certain anatomical position parameters. Output of the algorithm includes estimates of the measuring system accuracy. For a particular knee-motion-measuring ISL and calibration device, several interdependent design parameter relationships have been identified. These interdependent relationships are due to the configuration of the ISL and calibration device, the number of calibration positions, and the limited resolution of the devices that monitor the position of the linkage joints. It is shown that if interdependence is not eliminated, then the resulting ISL parameter set will not be accurate in measuring motion outside of the calibration positions, even though these positions are within the ISL workspace.     

Combination of microdialysis and Glucosensor permits continuous (on line) s.c. glucose monitoring in a patient operated device: I. In vitro evaluation.

A device for continuous glucose monitoring in fluids was obtained by combining the microdialysis technique with a measuring flow chamber of the "Glucosensor Unitec Ulm" using the GOD method for determining amperometrically blood glucose profiles. The in vitro experiments demonstrate that the relative recovery of glucose by this device is inversely related to the flow rate of the microdialysis perfusion fluid, which, in turn, is inversely related to the response time of the device. The glucose signal increases linearly with the area of the microdialysis working membrane (r = 0.98), and with the glucose concentrations of the standard solutions (r greater than 0.95). The variation coefficient for repeated measurements is below 8%. The accuracy of the device as demonstrated by mean measuring deviation ranges between 1 and 3.8%.     

Universal measuring site for the determination of tissue-impedance variations in relation to blood perfusion]

In view of the importance of impedance plethysmography requirements are formulated for a modern impedance measuring device basing on a long experience with this method of measurement. The principle mode of action of the measuring equipment and the pneumatics with the timing element are described. A number of recordings is shown to illustrate the universality of the measuring equipment.     

Multifunctional testing of PTCA balloon catheters]

New in vitro measuring methods for balloon catheters used for percutaneous transluminal coronary angioplasty (PTCA) and their verification in a complex test device are presented. This system can mimic all relevant application situations. The central element of the test device is a coronary vessel model matching the physiological situation in terms of geometrical structure and frictional properties. Reactive force sensors are used to measure the application-relevant forces exerted by the catheter on the model vessel walls and accessories, such as guide wire and guiding catheter. To generate a kink-free advancement of the catheter and permit measurement of the active forces, an alternating drive unit has been specially developed. The testing and application of the newly developed methods revealed statistically significant differences between various types of catheter. The test device closes a gap between complex but subjective clinical tests, and individual objective, but application-removed in vitro test setups for PTCA catheters. While the initial prototype had shortcomings with regard to the reproducibility of measurements, successor systems developed for industrial use are now in production. The properties of these measuring systems developed for the benefit of manufacturer and reprocessor of PTCA catheters are discussed.     

Semielectronic turbidimeter for automated monitoring of bacterial growth in test tubes.

An automated turbidimeter for measuring bacterial growth in ordinary test tubes is described. The device records and prints adsorbance, expressed as Klett units, of 60 cultures every 15 min. Provision is made for either aerobic or anaerobic incubation. The device is adaptable to modification, depending upon local requirements and availability of computation facilities.     

Abscission: quantitative measurement with a recording abscissor

The construction, operation, and effectiveness of an abscission measuring instrument called an abscissor is described. The device measured the force required for a spring-opposed plunger to shear abscission zone explants and was capable of automatically recording break strength data. Examples of data obtained with the abscissor are presented to demonstrate its capability of rapidly measuring significant changes in explant break strength.     

Fluorometric device for direct measuring of culture fluorescence within fermenters

A fluorometric device for direct measuring of culture fluorescence within the fermenter is described. The calibration by quinine sulfate as well as the response to a step increase of the input is presented.     

Verfahren und Analysenautomat zur Bestimmung von Nährlösungskomponenten und Stoffwechselprodukten

A continuous flow system with an enzyme electrode and with a new type of measuring instrument, the BIOXY-Meter, is described as an example for the determination of glucose. The BIOXY-Meter combined with various biosensors may be used in biotechnology and in other fields for the solution of a number of analytical problems. Measuring principle is the reduction of oxygen. The peak of first derivation of the current-time-curve is proportional to oxygen consumption and to decrease of substrate concentration. Enzyme fixation with common adhesive and a device for automated saturation of measuring samples with air in the sampler are also described. With the apparatus 60 samples per hour are analyzed for glucose. The linear measuring range is 0.1 mMol to 1.5 mMol with a coefficient of variation of V_k = 0.93 per cent. The described type of enzyme electrode is stable for 2 to 12 weeks or 1,000 to 5,000 measurements.     

A method for in vivo measurements of implants used in the reconstruction of spinal fractures]

Little is known about the forces and moments acting on the spinal column during various movements and activities, and thus about the loading of implants used in the treatment of spinal fractures. A measuring method using an external fixation device was developed to determine the in vivo loading of spinal implants. On the basis of these data the forces acting on the spine can be calculated. The present paper describes this measuring method as applied to the fixation device, and initial experience with this device in a first application is presented.     

Stickstoff als Leitelement für die Untersuchung von Fermentationsprozessen. Anwendungsmöglichkeiten eines Ammoniummeßgerätes

This paper presents the application of a new developed measuring device for continuous determination of ammonium concentration especially in the field of biotechnology. Kinetic measurements of changes of ammonium concentration during stationary and instationary growth of microorganisms allows to quantify such interesting parameters as nitrogen consumption rate r_N, productivity r_x, specific growth rate ß, adaption time, diauxic behavior and mass content M_F of fermenter etc. The results received by the combination of appropriated methods with the ammonium measuring device are not limited to biotechnology, so other applications in the field of chemistry, agriculture, technology, waste water industry etc. are possible.     

"Aachen 3-D-finger". Development of a 3-D-digitizer for use in dental, oral and maxillary treatment

The "AACHEN 3D Finger" is a three-dimensional measuring system for use in all fields of dentistry. The system can equally as well be installed on a plane table, as fixed to the head of a patient. The measuring device is computer-assisted, and is able to localize, register and calculate any combination of points in the oral and maxillofacial area. The reference system can be changed at any time. The "AACHEN 3D Finger" can be used as a computer-a ded system in dentistry as well as in implantology or dental and maxillofacial surgery.     

Feasibility of using a magnetic tracking device for measuring carpal kinematics

While several different methods have been used to measure carpal kinematics, biplanar radiography is generally considered to be the most accurate and popular one. However, biplanar radiography is tedious and so only pseudo-dynamic kinematics can be measured. Recently, magnetic tracking system has been developed for the measurement of joint kinematics which is versatile and easy to use and so the possibility of measuring motions dynamically. In this study, the capability of a magnetic tracking device to accurately measure carpal kinematics was investigated by comparing it with biplanar radiography. The kinematics of the third metacarpal, scaphoid, and lunate in five fresh cadaveric specimens were measured using both methods as the wrists were placed in eight positions. The finite screw rotation of each bone with respect to the distal radius during selecting the seven wrist motions was calculated for both measuring techniques and compared. In general, the kinematics for all three bones measured by using either magnetic tracking device or biplanar radiography was identical and showed no statistical difference. The averaged differences ranged from 0.0 to 2.0°. These differences were due to the potential effect of the weight of the sensors and the interference of the attaching rod to the surrounding tissue. It is concluded that the application of the magnetic tracking device to carpal kinematics is warranted, if proper technical procedures as suggested are followed.     

A shapeable foot-pressure measuring device

Measurement of foot pressure distribution for clinical purposes should ideally be made inside the shoe with a shaped insole and raised heel. Pressure measuring platforms cannot do this and transducers inserted inside the shoe can be obtrusive and inaccurate. The main clinical benefit of foot pressure measurement is the assistance it gives to shoe insole design. A shapeable foot pressure measuring device is being developed. The device can be accurately shaped to the contours of the foot and can indicate the pressure distribution over the entire surface of the foot. By adjusting the shape locally, high pressure areas can be relieved and the resulting shape can be used to vacuum-form a shoe insole. The device also has potential for the manufacture of special seating.     

Active analog pipeline delays for high signal rates in multistation flow cytometers

Flow cytometers with sequential measuring stations require alignment of event timing information to assure that multiparameter data for each cell are properly correlated. Information from the first detector must be delayed until signals are produced at the last detector, with adjustments to align them in time for simultaneous digitization after the last measurement is completed. By using an analog "pipeline" delay, the deadtime between the first and last measuring stations can be minimized. The described device is capable of acquiring and propagating many signals within the delay period, with good fidelity at high signal rates. An integrated circuit charge-coupled device (CCD), which is an analog shift register, is shown to be useful as a signal delay in the time range from 22 microseconds to several milliseconds.     

Low-cost digital impedance meter for the detection of micro-organisms

The digital impedance meter is a microprocessor-based instrument able to detect, quantify and identify micro-organisms. The equipment makes use of the bipolar technique of measuring the impedance modulus of six cells containing inoculated culture broth. It performs temperature compensation automatically. Growth curves are stored in memory as time course events and can be displayed on any suitable device.     

检测生物体表空气负离子浓度的数学模型及装置

本文介绍一种检测生物体表任一点空气负离子浓度的数学模型,并根据该模型设计了一种检测装置．此装置具有体积小、价廉、操作简便和数字显示等优点．临床应用证明效果良好．     

Newly-developed measuring device for the quantitative assessment of thermal and pain thresholds of peripheral nerves.

Measuring devices for the quantitative assessment of thermal and pain thresholds are either simple and only suited for inexact tests or accurate and objective but expensive. The aim was there for to develop a cost effective device to enable a short and practical test of neurosensibility under clinical conditions. The result of this development is a new thermosensibility-measuring device (TSM) consisting of the measuring unit itself and a thermal probe. The data are registered and analysed through direct data transfer to a connected PC. Investigations carried out with this device revealed the construction to be efficient and easy to handle under clinical conditions. The TSM provides the examiner with the opportunity to monitor the neurosensory function of peripheral nerves in a reproducible way.     

On-line determination of biomass in a microalga bioreactor using a novel computerized flow injection analysis system

A flow injection analysis (FIA) device has been developed, which is able to assay successfully for biomass in a microalga bioreactor. The device is fully computerized and is operated via diluting small aliquots of the culture followed by measuring optical density (OD); this figure is then accurately correlated with biomass, in terms of both cell number and ash-free dry weight, during the entire culture time. Furthermore, the device is not expensive, is highly versatile, and is easy to operate owing to specifically developed, user-friendly software. The growth rate and biomass productivity of Pavlova lutheri, cultivated under batch and semicontinuous modes, were monitored as experimental testing model.     

Spatially resolved monitoring of cellular metabolic activity with a semiconductor-based biosensor

Metabolic activity of cultured cells can be monitored by measuring changes in the pH of the surrounding medium caused by metabolic products such as protons, carbon dioxide or lactic acid. Although many systems designed for this purpose have been reported, almost all of them are based on bulk measurements, where the average metabolic activity of all cells in contact with the device is recorded. Here, we report on a novel biosensor, based on a modified light-addressable potentiometric sensor (LAPS) device, which enables the metabolic activity of cultured cells to be measured with spatial resolution. This is demonstrated here by detecting the differential sensitivity to a cholinergic receptor agonist of two different co-cultured cellular populations. By making simultaneous measurements of the metabolic activity of different cell types seeded on different segments of one sensor, this device not only provides a rapid means of assessing cellular specificity of pharmaceutical compounds but also has the potential of being used to non-invasively monitor humoral as well as synaptic communication between different cell populations in co-culture. The temporal and spatial resolution of the device were investigated and are discussed.     

Apparatus for monitoring the oxygen uptake and carbon dioxide production of fermentations

The requirements of the continuous analysis of effluent gas streams from aerated flash and tank fermentors are described, as are instrumental devices for measuring the oxygen and carbon dioxide content of fermentor gases. The use of a specially designed sequential gas sample for monitoring four fermentations simultaneously and a system for precise control of low air flow and pressure is explained. Equations for calculating carbon dioxide production or oxygen consumption rates and respiratory quotients are given. A discussion of the operating characteristics of a device for automatic translation of aeration data between fermentors is presented.