Thorsten Meiss

Closed loop stability analysis of an assistance system for catheterization

Catheterizations are standard procedures of todays vascular treatment for diagnosis and therapy. To improve navigation even into smaller branches a novel device with haptic feedback assisting during catheterization is currently being developed. One aspect of the design is the identification of possible sources for instability, which is focused on in this paper. This requires the analysis and modeling of the interaction between the device, the patient and the medical staff. The resulting open loop response plotted in Bode-diagram demonstrates areas of possible instabilities. As a result design constrains to guarantee stability in any possible situation is derived

Performance of a novel micro force vector sensor and outlook into its biomedical applications

For the HapCath system, which provides haptic feedback of the forces acting on a guide wires tip during vascular catheterization, very small piezoresistive force sensors of 200•200•640μm3 have been developed. This paper focuses on the characterization of the measurement performance and on possible new applications. Besides the determination of the dynamic measurement performance, special focus is put onto the results of the 3- component force vector calibration. This article addresses special advantageous characteristics of the sensor, but also the limits of applicability will be addressed. As for the special characteristics of the sensor, the second part of the article demonstrates new applications which can be opened up with the novel force sensor, like automatic navigation of medical or biological instruments without impacting surrounding tissue, surface roughness evaluation in biomedical systems, needle insertion with tactile or higher level feedback, or even building tactile hairs for artificial organisms.

Examples of Haptic System Development

In this section, several examples of task-specific haptic systems are given. They give an insight into the process of defining haptic interactions for a given purpose and illustrate the development and evaluation process outlined in this book so far. Examples were chosen by the editors to cover different basic system structures. Section 14.1—Tactile You-Are-Here-Maps illustrates the usage of a tactile display in an assistive manner, enabling a more autonomous movement of people with visual impairments. Section 14.2—User Interface for Automotive Applications presents the development of a haptic interface for a new kind of user interaction in a car. It incorporates touch input and is able to simulate different key characteristics for intuitive haptic feedback. Section 14.3—HapCath describes a comanipulation system to provide additional haptic feedback in cardiovascular interventions. The feedback is intended to reduce exposure for both patient and physician and to permit new kinds of diagnosis during an intervention.

Piezoelectric Ultrasonic Actuator for a Haptic Display for Catheterisation

During a catheterisation, the surgeons navigation to the coronary vessels is restricted to a two-dimensional X-ray image. The HapCath system presents a haptic feedback to the surgeon to enable a more intuitive navigation similar to a blind mans cane. In this paper the actuation system for the haptic interface is shown. A piezoelectric ultrasonic actuator is used to generate force and torque on the guide wire. The main working principle of the actuator is described. The advantages compared to dynamic actuating systems are described

Miniaturized Haptic User-Interface for Heart Catheterizations – Concept and Design

During heart catheterization the cardiologist controls the direction of the guide wire mainly by visual x-ray information. In this paper a haptic display is presented, which generates an amplified force feedback of the contact force measured at the distal tip of a guide wire. A network model is elaborated and a concept for miniaturization and integration into a haemostasis valve is proposed.

Active Knee Orthosis for Supporting the Elderly

1 Dept. of Control Engineering and Mechatronics, TU Darmstadt, Darmstadt, Germany, mgruen@iat.tu-darmstadt.de 2 Measurement and Sensor Technology Lab., Institute for EMK, TU Darmstadt, Darmstadt, Germany 3 Microtechnology and Electromechanical Systems Lab., Institute for EMK, TU Darmstadt, Darmstadt, Germany 4 Dept. of Orthopedics, Trauma Surgery and Paraplegiology, Heidelberg University Clinics, Heidelberg, Germany

Measurement setup to evaluate haptic interaction in catheterization procedures for training purposes

Recanalization of chronic total occlusions (CTO) of coronary vessels is a catheter intervention with proven benefit for the patient. However, it incorporates a risk of penetrating the vessel as well as increasing patients exposure to radiation and contrast agent. The physicians expertise is a key to successful interventions. In this work, we present a system to assess haptic interaction of medical professionals in an CTO intervention. As a test scenario, a silicone model with comparable mechanic properties of a CTO, including fibrous caps and microchannels is used. A special guide wire with a diameter of 360 μιη and an integrated force sensor at the tip can measure intracorporal forces. Additionally, a torquer with an integrated single-axis force sensor is used to measure the forces executed by the cardiologist during the procedure. The guide wire motion is measured by two encoders (translational and rotatory) in order to assess motion-based quality criteria. A camera setup with software filtering is used to obtain an x-raylike image of the training scenario. Applied x-ray and contrast agent doses can be measured as well. The setup is intended to develop new training schemes based on interactions exerted by experts.

Sensor System for an active Orthosis supporting the Elderly

The aging society of matured economies will face large challenges in the near future: There will be more and more elderly compared to younger people. To keep elderly persons self determined, and therefore reducing the need for personal help by maintaining the elderly ability to manage debilitating situations, a actively supporting orthosis is build. The first concept and first implementation of the sensor system to determine the user’s movements and torque is presented.

Novel approach for estimating muscular activity using mechanical effects of the human thigh as an alternative to EMG

The A novel approach for estimating muscular activity of the human thigh using mechanical effects on the surface is investigated. Muscular activity is expected to provide one of the input signals for the motor control of an active orthosis to support the elderly. Up to now Electromyography (EMG) is the gold standard for measuring muscular activity. These measuring systems are prone to electromagnetic disturbances, influence of sweat on the skin-electrode-interface and aging effects of the glue. Furthermore the necessity of wired, skin contacted and glued electrodes reduces the ergonomic qualities. Thus, EMG is inappropriate for long-term usage in the every-day environment.

Methods of resolution for haptic assistance during catheterization

Abstract Die Navigation des Führungsdrahtes bei Katheterisierungen basiert im Wesentlichen auf einem in Echtzeit aufgenommenen 2D Röntgenbild. Dreidimensionale Verfahren und mechanische Assistenzsysteme für die telemanipulierte Navigation sind Gegenstand aktueller Forschung, dennoch ist das präzise Positionieren im medizinischen Alltag noch in erster Linie das Ergebnis von intensivem Training und hohen manuellen Fertigkeiten des operierenden Arztes. Dieser Artikel beschreibt ein System zur Ergänzung von existierenden Verfahren von Katheterisierungen. Es besteht aus einem miniaturisierten Kraftsensor an der Spitze eines Führungsdrahtes, dessen Prototyp hier vorgestellt wird. Die gemessenen Kräfte werden dem Mediziner in verstärkter Form durch einen externen Aktor vermittelt. Somit entsteht ein Eindruck der Kraft zwischen Führungsdraht und Gefäßinnenwand, welcher dem Abtasten des lebenden Gefäßes von Innen entspricht. During catheterization navigation within the patient is mainly dependent on a live x-ray image on the screen. Although methods for 3D visualisation and remote navigation of the catheter are discussed and tested still precise positioning is merely the result of intense training and a high skill and level of training of the performing surgeon. This article refers to a system which can be considered as an add-on for existing procedures of catheterization. It compromises of a miniaturised force sensor located at the tip of guide-wires whose prototype is shown here. The measured forces will be presented to the surgeon amplified by an external actuator described in this article. As a result a haptic perception of the forces between the tip of the guide-wire and the vessels walls will be available and enable the surgeon to gain an impression which is comparable to palpation of living vessels from the inside