PMBi pump with piezo motor

Worldwide unique lab pump

For its international medical technology customers the Finnish company Ginolis has developed a high-precision dispensing pump: A linear motor powered by piezoelectricity from PiezoMotor ensures the required nanolitre precision.

Precise and repeatable dispensing of volumes: With the PMBi pump, Ginolis has achieved a breakthrough in this area. Unequalled on the market with respect to precision and its low-maintenance design, the fully integrable pump is available in two models for different volume capacities. PMB stands for PiezoMotor Bellows – which is the core element of the pump: a bellows system powered by piezoelectricity. The pumps are equipped with motors from the Swedish manufacturer PiezoMotor, which feature high precision and a compact design with enormous power.

Ginolis, with headquarters in Oulu, Finland, offers an extensive spectrum of solutions on the basis of modular automation platforms, ranging from standard products to custom-tailored systems. Established in 2010, the company has patents in the areas of dispensing, micro-production and precision robotics, and works together with many of the world’s leading diagnostic companies.

Versatile, intelligent and low-maintenance design

The PMBi pump, which was launched only recently and has already found numerous buyers, is versatile, intelligent and requires very little maintenance. It is used for dispensing reagents and fluids on a compact scale and can either be integrated in the automation platforms manufactured by Ginolis or used as a standalone product and is available as a starter kit including the pump, degasifier, hoses, valves and ceramic dispensing nozzles.

“We developed the original pump in 2013 on the basis of a customer requirement”, relates Markku Känsäkoski, Technical Director and Head of Development at Ginolis. “The solution he was using at the time simply did not provide the required precision. That is why we were requested to develop a pump that meets the requirements for precision. Involvement of the company PiezoMotor was also brought about directly by the customer.” The result was a one-off custom pump that was modified in 2019 by improving the communication interfaces to make it suitable for large-scale production.

PiezoMotor drives the bellows

The principle of the Ginolis PMBi pump is a high-precision piezo motor that contracts and expands a bellows. The bellows precisely displaces the volume previously drawn into a closed chamber. The magnetic valve opens for a short time (100 microseconds) to release a droplet. This allows dispensing of up to 100 droplets per second. The use of a piezo motor eliminates friction in the bellow system, which results in a pump with an extremely long life and no requirement for replacement seals. The pump has a size of only 127 x 44.5 x 148.5 mm and is equipped with RS-232 and RS-485 interfaces; an Ethernet connection is available as an option. An integrated pressure sensor controls blockage, leaks and air in the fluid line, and monitors the pump’s upstream pressure generation and pressure stabilization during pre-dispensing.

“The pump dispenses fluid with a droplet size of one nanolitre. This requires very high precision in the movement of the fluid chamber. In addition, there can be no recoil whatsoever in the motor, which is achieved by the piezo motor”, emphasises Markku Känsäkoski of Ginolis. The unique pumps are equipped with standard Twin LT20 and Twin LT40 linear motors with a stall force of 20 N and 40 N, respectively.

High force per volume

Piezoelectric motors are typically used in applications requiring maximum precision and miniaturization. The robust, high-precision motors use the innovative but time-proven Piezo LEGS technology for back-lash free movement in the nanometre and even sub-nanometre range. The inverse piezoelectric effects causes deformation of certain ceramic materials when voltage is applied.

Application of voltage starts up a brushed DC motor. The Piezo LEGS, which are made of ceramic and arranged in pairs – generally with a total of four or six legs – can drive both linear and rotating motors. The motors are especially suitable for move and hold applications, since the drive rod is always held by at least one pair. This eliminates the need for additional force for the holding position and also ensures high holding force in off state. Compared with conventional electric motors, they feature numerous advantages, including high force per volume – from a few newtons up to 450 N –, excellent dynamics and miniaturization capabilities, as well as high flexibility with respect to speed and outstanding precision.

Cooperation to be broadened in the future

“Technologically we developed a pump with a unique design that we also patented”, says Känsäkoski. The pump is installed as standard equipment in the dispensing platform “Cecilia-L” from Ginolis, a compact, high-precision and contactless dispensing and aspiration platform. Cecilia-L is ideal for numerous medical technology applications, as well as in microfluidic chip and cartridge printing, as well as in automated fluid handling for biochips and miniaturized assays. The platform is equipped with two to four PMBi dispensing pumps.

The cooperation with PiezoMotor was very satisfying and constructive from the development stage through to large-scale production. The availability of suitable encoders made it possible to reduce the time needed for development. “Currently our focus is on robotics and automation”, Känsäkoski remarks. “But we have a demand for high-precision assembly processes. There is no doubt that we will work together with PiezoMotor more often in the future.”