Please cite with: Pech, S.; Richter, R.; Lienig, J.: Peristaltic Pump with Continuous Flow and Programmable Flow Pulsation, IEEE Electronics Packaging Society, 8th Electronics System-Integration Technology Conference (ESTC), Vestfold, Norway, 15 - 18 September 2020, DIO: 10.1109/ESTC48849.2020.9229731. Peristaltic Pump with Continuous Flow and Programmable Flow Pulsation Sebastian Pech Institute of Electromechanical and Electronic Design (IFTE) Dresden University of Technology Dresden, Germany sebastian.pech@outlook.com René Richter Institute of Electromechanical and Electronic Design (IFTE) Dresden University of Technology Dresden, Germany rene.richter@tu-dresden.de Jens Lienig Institute of Electromechanical and Electronic Design (IFTE) Dresden University of Technology Dresden, Germany jens.lienig@tu-dresden.de Abstract—In future, sensors with flexible electronics will be deployed more often in biomedical applications for the acquisition of biological signals in the human body. To ensure biocompatibility, these sensors are often encapsulated by polymers. For research and testing of new encapsulation materials and their biocompatibility evaluation, new test procedures will be necessary, which reflect the flow conditions of the physiological environment. This paper presents a new peristaltic pump which stimulates the tube by a circulating eccentric oscillation. The pump characteristics differ significantly from conventional roller pumps and combine continuous flow and programmable flow pulsation. In continuous mode the non-occlusive pump can reduce the flow pulsation by about 85% in comparison to a conventional roller pump. Programmable flow pulsation is achieved by controlling the oscillation amplitude. This control characteristic enables the generation of defined volume flow pulses. Pulse shapes of a second generation vessel in the human arterial network can be generated in experimentally, for instance. These pulse shapes are required for in vitro investigations of biocompatible encapsulations under physiological flow conditions. Keywords—peristaltic pump, in vitro circulation, biosensor, biocompatibility testing I. INTRODUCTION For biomedical applications, sensors with flexible electronics will be required more frequently to detect biological signals in the human body [1]. Currently, these sensors are often encapsulated by polymers. This encapsulation ensures the biocompatibility of the sensor unit and prevents negative reactions between the human organism and the implanted unit. However, the polymers currently used for encapsulation are not capable of hermetically sealing the unit from the organism due to residual ion permeability [2]. New test procedures will be needed in the search for new encapsulation materials and their biocompatibility evaluation. These test procedures will need to reflect the flow conditions of the physiological surroundings as accurately as possible. Artificial body fluids in in vitro circulation loops will be used in these investigations. Currently, roller pumps are often used to pump liquids through the test circuit [3]. These peristaltic pumps work according to the positive displacement principle and displace the volume peristaltically by completely occluding the pump tube. Due to the complete tube occlusion a strong volume flow pulsation occurs. This pulsation and the associated pressure peaks can negatively impact sensitive processes. For example, the pressure peaks can damage thin membranes during biocompatibility in vitro studies. Furthermore, roller pumps are not capable of generating specific pulse shapes needed to simulate physiological flow conditions. Centrifugal pumps are also used in these test circuits. These hydrodynamic pumps can provide a very constant volume flow for the test circuits, but are also incapable of generating the required defined pulse shapes. The contribution of this paper is the introduction of a novel pumping principle based on a peristaltic pump, which can be used to generate a continuous volume flow without pulsation and programmable pulse shapes. The biocompatibility of encapsulations under physiological flow conditions can be tested with programmable pulse shapes. This is done, for example, with a typical pulse shape of a second generation vessel in the human arterial network (according to [4]). II. PUMPING PRINCIPLE In contrast to conventional roller pumps, a circulating eccentric oscillation stimulates the pump tube, which is not occluded completely during this process [5-7]. For this purpose, the tube is placed in the gap between the oscillating coupler and the housing of the pump section (see Fig. 1). A dynamic throttling device (resistor) [7] for decoupling the volume flow is fitted at the pump outlet. The pumping principle is based on a superposition of the displaced volume, the propagation of the pulse wave along the tube winding and the throttling effect of the resistor. The main ideas behind our new pumping principle are described in the following three paragraphs. Fig. 2 illustrates the pump section projected onto developed surfaces for better understanding. A. Volume pulse The coupler oscillates with frequency f and amplitude rosc during the pumping operation. In Fig. 1 and Fig. 2, the angle φ describes the current position of the coupler during its eccentric motion. This motion deforms the tube periodically, Fig. 1. Top view of the rotationally symmetrical pump section. The coupler performs a circulating eccentric oscillation with frequency f, oscillation amplitude rosc and angle φ of oscillation.