A New Concept of a Drug Delivery System with Improved Precision and Patient Safety Features

Miniaturized peristaltic rotary pump for non-continuous drug dosing

Micro dosing pumps are the beating heart of infusion systems. Among many technologies to inject micro quantities of fluids, peristaltic pumps show high precision and the possibility to not alter the fluid properties. However, in real drug delivery applications, the continuous release behavior of typical peristaltic pumps is not favorable. In this paper, we investigate the intermittent performance of two prototypes of peristaltic pumps, based on four and five rollers, used to occlude the tube. The pump performances are reported for different rotation speeds and lag times between consecutive infusions. The proposed pumps showed a good volumetric precision (2.88 μL for the five rollers pump and 4.11 μL for the four rollers pump) without any dependency on rotation speed and lag time.

Positioning Error Analysis and Control of a Piezo-Driven 6-DOF Micro-Positioner

This paper presents a positioning error model and a control compensation scheme for a six-degree-of-freedom (6-DOF) micro-positioner based on a compliant mechanism and piezoelectric actuators (PZT). The positioning error model is established by means of the kinematic model of the compliant mechanism and complete differential coefficient theory, which includes the relationships between three typical errors (hysteresis, machining and measuring errors) and the total positioning error. The quantitative analysis of three errors is demonstrated through several experimental studies. Afterwards, an inverse Presiach model-based feedforward compensation of the hysteresis nonlinearity is employed by the control scheme, combined with a proportional-integral-derivative (PID) feedback controller for the compensation of machining and measuring errors. Moreover, a back propagation neural network PID (BP-PID) controller and a cerebellar model articulation controller neural network PID (CMAC-PID) controller are also adopted and compared to obtain optimal control. Taking the translational motion along the X axis as an example, the positioning errors are sharply reduced by the inverse hysteresis model with the maximum error of 12.76% and a root-mean-square error of 4.09%. In combination with the CMAC-PID controller, the errors are decreased to 0.63% and 0.23%, respectively. Hence, simulated and experimental results reveal that the proposed approach can improve the positioning accuracy of 6-DOF for the micro-positioner.