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SHAPE MEMORY ALLOY MICRO ACTUATORS FOR MEDICAL APPLICATIONS

Objective


An analysis of the current application and technological limitations of shape memory alloys for microapplications was performed. To enable to use of these alloys as an engineering material for micro-actuation, four production technologies for small SMA elements were studied: grinding, rolling, melt spinning, and sputtering. For each of these processes, the material technology, the engineering process, and their mutual interaction were studied. Based on a superior overall performance, melt spinning technology was selected for developing the demonstrators.
The biocompatibility packaging requirements together with a study of the thermal constraints when using SMAs in the human body were identified. This included the study of biological effects of electromagnetic waves when used for remote operation of the actuators.
A prototype implantable drug delivery system based on shape memory actuated microvalves has been developed. Several types of microvalves have been developed and tested. The selected concept is designed for low cost production and assembly. The drug delivery device includes a system for remote powering and control of the embedded shape memory microvalves.
A prototype semi-autonomous colonoscopic intervention system has been developed. The main module or mothership of this system uses a locomotion system based on pneumatic actuation. The pneumatic actuators are controlled by shape memory actuated microvalves. The system is able of a self-propelled locomotion through the intestines which is a complete new approach compared to the conventional devices which are propelled by a force provided by the surgeon. In addition, concepts for rotary and bending micro-actuators based on shape memory alloys are presented. These actuators could be used for actuating additional tooling on the mothership.
It is proposed to develop Shape Memory Alloy (SMA) based micro-actuators which can be integrated in advanced tele-operated micro-systems for medical applications. The use of shape memory alloys as actuator will increase the performance of micro-mechanical devices by several orders of magnitude Because of the large number of possible applications in the medical field, the proposal is focusing on the construction of two medical prototypes. The development will also deal with application-oriented general design rules and with operational constraints in biological environments. In order to meet these technical objectives, the required principal tasks are outlined as follows :

- Enhancement of the SMA material knowledge, especially when used for micro-scale applications. This includes a study on the influence of the production technology.

- Study of biocompatibility requirements like : packaging, human body thermal constraints, biological effects of electromagnetic waves used for remote operation.

- Preliminary design of one single actuator. The finished actuator is a small-sized prototype of a micro-pump for drug delivery.

- Design of a multiple actuator system with improvement and full miniaturisation of the first prototype. Improved design of power supply and control signal transmission.

- The design of an improved control system. The final system. The final result of this task is a continuously controlled and remotely operated multiple actuator system.

- Building of a second prototype that can serve as a multifunctional endoscopic tool. Validation by functional and operational testing of the device.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

KUL
Address
Celestijnenlaan,300b
3001 Heverlee
Belgium

Participants (4)

CYBERNETIC TECHNOLOGY
Belgium
Address
Rue De Limauge 13
1040 Brussels
Consiglio Nazionale delle Ricerche (CNR)
Italy
Address
Via Savi 8
56127 Pisa
Scuola Superiore di Studi Universitari e di Perfezionamento Sant'Anna
Italy
Address
Via Carducci 40
56127 Pisa
UNIVERSITE DE VERSAILLES
France
Address
4 Place Jussieu
75229 Paris