Arthur G. Erdman

The big picture on nanomedicine: the state of investigational and approved nanomedicine products

UNLABELLED Developments in nanomedicine are expected to provide solutions to many of modern medicines unsolved problems, so it is no surprise that the literature contains many articles discussing the subject. However, existing reviews tend to focus on specific sectors of nanomedicine or to take a very forward-looking stance and fail to provide a complete perspective on the current landscape. This article provides a more comprehensive and contemporary inventory of nanomedicine products. A keyword search of literature, clinical trial registries, and the Web yielded 247 nanomedicine products that are approved or in various stages of clinical study. Specific information on each was gathered, so the overall field could be described based on various dimensions, including FDA classification, approval status, nanoscale size, treated condition, nanostructure, and others. In addition to documenting the many nanomedicine products already in use in humans, this study identifies several interesting trends forecasting the future of nanomedicine. FROM THE CLINICAL EDITOR In this one of a kind review, the state of nanomedicine commercialization is discussed, concentrating only on nanomedicine-based developments and products that are either in clinical trials or have already been approved for use.

Design of an MRI-Compatible Robotic Stereotactic Device for Minimally Invasive Interventions in the Breast†

The objective of this work was to develop a robotic device to perform biopsy and therapeutic interventions in the breast with real-time magnetic resonance imaging (MRI) guidance. The device was designed to allow for (i) stabilization of the breast by compression, (ii) definition of the interventional probe trajectory by setting the height and pitch of a probe insertion apparatus, and (iii) positioning of an interventional probe by setting the depth of insertion. The apparatus is fitted with five computer-controlled degrees of freedom for delivering an interventional procedure. The entire device is constructed of MR compatible materials, i.e. nonmagnetic and non-conductive, to eliminate artifacts and distortion of the MR images. The apparatus is remotely controlled by means of ultrasonic motors and a graphical user interface, providing real-time MR-guided planning and monitoring of the operation. Joint motion measurements found probe placement in less than 50 s and sub-millimeter repeatability of the probe tip for same-direction point-to-point movements. However, backlash in the rotation joint may incur probe tip positional errors of up to 5 mm at a distance of 40 mm from the rotation axis, which may occur for women with large breasts. The imprecision caused by this backlash becomes negligible as the probe tip nears the rotation axis. Real-time MR-guidance will allow the physician to correct this error Compatibility of the device within the MR environment was successfully tested on a 4 Tesla MR human scanner

CAD/CAM for dental restorations-some of the curious challenges

The current state of the art for production of dental restorations is reviewed, and DentiCAD, a system being developed by Maryland University and Minnesota University which is capable of producing dental crowns, is described. DentiCAD can produce dental restorations that fit at least as well as those that are cast. Some of the challenges and difficulties that have arisen during development are addressed. Some of the questions that, because of the new technology, can now be addressed and that are presenting new challenges are discussed.<<ETX>>

Kineto-elastodynamics — A review of the state of the art and trends

Abstract Kineto-Elastodynamics is the study of the motion of mechanisms consisting of elements which may deflect due to external loads or internal body forces. The requirement for machines to run at higher speeds brought to the surface many problems, such as balancing and vibrations, which were not serious factors at lower speeds. This review presents a general summary and attempts to organize the nomenclature of mechanism dynamics. It also indicates the current trend in the literature of kineto-elastodynamics and points the way to a possible unification of all dynamic effects.

Finite element approach to mathematical modeling of high-speed elastic linkages

Abstract A general approach is described for deriving the equations of motion of planar linkages in high-speed machinery. Based on the work of several current authors, well-known displacement finite element method is used to develop the mass and stiffness properties of an elastic linkage. To demonstrate the various steps in the analysis, a 4-bar linkage is utilized; however the method is readily extendible to other planar multi-loop linkages. Starting with a typical elastic planar beam element, the nodal displacement and acceleration expressions are derived including the terms coupling the elastic and rigid-body motions. The linkage is modeled as beam elements and its equations of motion are stated in matrix form. Methods are described for systematic assembly of all elements, resulting in the undamped equations of motion of the total system. Conventional forms of structural damping are reviewed and appended to this paper for inclusion in the equations of motion. This paper also includes assumptions made in order to simplify the analyses here as well as facilitate numerical solutions.

A review of mechanism used in laparoscopic surgical instruments

Abstract Many surgical instruments consist of basic mechanical components such as gears, links, pivots, sliders, etc., which are common in mechanical design. This paper introduces a reference table that was created by investigating the mechanical characteristic and the differences between 16 patented laparoscopic surgical devices, most of which are surgical staplers [1] , [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] . Laparoscopic surgical instruments were chosen for this paper because of the complex mechanical systems used in performing their required functions. For the similar functions of stapling and kinematic maneuvering, each instrument investigated varies widely in design and the type of mechanical components used. The reference table created will benefit engineers, designers, and students in analyzing the mechanical subsystems used in surgical instruments and suggest alternative options available for replacing existing designs. Although the table was created for laparoscopic surgical devices, its application could be extended to other surgical and non-surgical devices.

Effects of rotational jaw growth on the occlusion and profile.

S tudies using cephalograms employ a method of tracing skeletal structures on a radiograph exposed at one time point, tracing these structures again on a second radiograph exposed at a second time point, superimposing the two tracings on some central reference point, and connecting presumed identical landmarks with a straight line .6p 6 This technique produces a self-fulfilling conclusion that the face and jaws grow downward and forward from beneath the cranium in a linear, translatory fashion. This perspective has influenced orthodontists to expect that the dental occlusion will also be carried in a similar, straight-line, downward and forward manner. Interest in vertical facial growth lead BjSrk,lv * Bjiirk and Palling,s Bjork and Skieller,4 e)degaard,*l-I2 Schudy,13-15 and Isaacson and associatess-lo in recent years to focus more attention on nonlinear jaw growth or jaw rotation. Jaw rotation was not recognized by early workers using cephalograms because of surface remodeling bone changes masking rotational effects as they occurred. This phenomenon of bone remodeling in jaws during normal growth has been carefully documented by BjSrk and Skieller,4 using metallic implants, and Enlow and Hunter,s using histologic techniques. Tooth movement also masked changes in dissimilar jaw growth by compensatory movements at the periodontal regions causing the occlusion to remain apparently in nearly constant relations.4 A recent report focused on a mechanism whereby vertical condylar growth can be converted into changes in anteroposterior jaw relationslo This mechanism explains how vertical condylar growth can, under specific conditions, result in significant anteroposterior dental and profile changes. According to this report, the long-held and widely reported concept of linear downward and forward facial growth is the exception rather than the rule. This report noted that, in order for translatory mandibular growth to occur, vertical

Flexible Tactile Sensor for Tissue Elasticity Measurements

This paper presents a novel tactile sensing technique for tissue elasticity measurements. A prototype flexible tactile sensor has been successfully fabricated using polydimethylsiloxane as the structural material. The proposed sensor comprises an array of capacitors with no active elements used. By varying the sizes of sensing membranes within the capacitors, different stiffnesses of sensing diaphragms can be achieved. The elasticity of the targeted object can be thereafter measured based on the relative deflections of the sensing diaphragms. The fabricated sensor has been calibrated by an off-the-shelf polymer durometer hardness selector pack. The results show a sensing resolution of 0.1 MPa for elasticity measurement and a force sensing resolution as small as 5 mN. This flexible tactile sensor can be embedded on the distal portions of various endoscopic instruments for in vivo tissue elasticity measurements.

Application of type synthesis theory to the redesign of a complex surgical instrument

Surgical instruments consist of basic mechanical components such as gears, links, pivots, sliders, etc., which are common in mechanical design. This paper describes the application of a method in the analysis and design of complex surgical instruments such as those employed in laparoscopic surgery. This is believed to be the first application of type synthesis theory to a complex medical instrument. Type synthesis is a methodology that can be applied during the conceptual phase of mechanical design. A handle assembly from a patented laparoscopic surgical stapler is used to illustrate the application of the design method developed. Type synthesis is applied on specific subsystems of the mechanism within the handle assembly where alternative design concepts are generated. Chosen concepts are then combined to form a new conceptual design for the handle assembly. The new handle assembly is improved because it has fewer number of parts, is a simpler design and is easier to assemble. Surgical instrument designers may use the methodology presented here to analyze the mechanical subsystems within complex instruments and to create new options that may offer improvements to the original design.

Active vibration controller design and comparison study of flexible linkage mechanism systems

Three active vibration controller design methodologies include the reduced modal controller, the classical and the robust H∞ controller for the high-speed flexible linkage mechanism systems with piezoelectric actuators and sensors are investigated. Firstly, the state space form control model is formulated based on the complex mode theory. Secondly, the reduced modal controller, the classical and the robust H∞ controller are designed. Finally, numerical simulations are carried out on a 4-bar linkage mechanism. The simulation results show that the vibration of the system is significantly suppressed with permitted actuator input voltages by each of the three controllers. The reduced modal control makes it more convenient to increase the modal damping of the system than that of the H∞ control does, while the robust H∞ control can avoid the spillover due to mode truncation.