In this application note, we compare the flow accuracy and stability at low flow rates of two micropump drivers designed by Bartels Mikrotechnik GmbH: the mp-Lowdriver and mp-Highdriver. Mounted on the mp-Multiboard (main control board) and connected to a Bartels micropump, these pump drivers offer various ways of tuning the electrical signal applied to the pump.
Introduction to Bartels environment: the mp-Lowdriver and mp-Highdriver can be interfaced easily on the mp-Multiboard.
The mp-Multiboard is a complete interface with an Arduino microcontroller, which allows to connect and control mp6 micropumps, active valves, Sensirion SLF3S flow sensors and pressure sensors from the same software.
Les micropompes Bartels sont basées sur une technologie piézoélectrique, et le signal électrique d'entrée a un impact sur les performances de la pompe. Par conséquent, 3 drivers de pompe ont été développés : le mp-Lowdriver, le mp-Highdriver et le mp-Highdriver4. Contrairement au mp-Lowdriver et au mp-Highdriver, le mp-Highdriver4 permet de contrôler 4 pompes simultanément, tandis que les deux autres ne permettent de contrôler qu'une seule pompe à la fois. Nous nous concentrerons sur le mp-Lowdriver et le mp-Highdriver, car le mp-Highdriver4 a les mêmes spécifications que le mp-Highdriver.
Bartels Multiboard App: a unified user interface
Based on an Arduino framework, Bartels has developed an application to easily control any device connected to the mp-Multiboard. It allows you to vary the frequency and amplitude for each of the 4 pumps, close or open the 2 valves and, monitor the flow rate or pressure in real time.
En outre, il est possible de contrôler le temps d'activation de chacune des pompes, mais aussi de déterminer laquelle doit être éteinte en premier. Cette application facilite la création de petits programmes multi-étapes sans aucune ligne de code !
mp-Lowdriver vs mp-Highdriver : quel driver choisir ?
The mp-Lowdriver and mp-Highdriver micropump drivers were designed to meet the needs of researchers working between 5 µl/min and 10 ml/min. In microfluidics, flow rates under 100 µl/min are commonly used, and Bartels micropumps present a cost-effective alternative to current technologies. Comparing both pump drivers will help to choose the right driver for your application, but also to demonstrate the accuracy these micropumps and drivers can deliver.
Table 1: Comparison between the mp-Lowdriver and mp-Highdriver micropump drivers (Bartels Mikrotechnik GmbH).
| mp-Lowdriver | mp-Highdriver | |
| Dimensions | 10.16 x 25.4 x 2.64 mm | 10.16 x 25.40 x 2.82 mm |
| Amplitude | 0 à 150 Vpp | 10 à 150 Vpp |
| Fréquence | 8 à 2000 Hz | 50 à 800 Hz |
| Forme du signal | sinusoïdal, personnalisé | sinusoïdal, rectangulaire, personnalisé |
Table 1: Comparison between the mp-Lowdriver and mp-Highdriver micropump drivers (Bartels Mikrotechnik GmbH).
The following flow measurements were made with a Sensirion SLF3S-0600F thermal flow sensor (+/- 5% accuracy on a range of +/- 2000 µl/min, min. accuracy of 0.5 µl/min), also used in the Bartels mpSmart-Lowdosing system.
Mesures de débit mp-Lowdriver
Deux mesures à 5 et 10 µl/min ont été effectuées avec le mp-Lowdriver pendant quelques secondes. Ces mesures nous ont permis de tester les capacités du mp-Lowdriver à de très faibles débits.
| mp-Lowdriver | 5 µl/min | 10 µl/min |
| Valeur mesurée (µl/min) | 5.22 | 10.86 |
| Erreur standard | 0.57 | 0.46 |
| Erreur standard (%) | 10.89 | 4.23 |
Table 2: Comparison between the target and measured values at 5 and 10 µl/min with a mp6-liq, mp-Multiboard and mp-Lowdriver (Bartels Mikrotechnik). Measured with a SLF3S-0600F (Sensirion) thermal flow sensor.
Figure 2: Actual flow rates with a mp6-liq micropump and mp-Lowdriver (Bartels Mikrotechnik) for target flow rates of 5 and 10 µl/min. Measured with a SLF3S-0600F flow sensor (Sensirion)
Bartels micropumps are indicated for flow rates higher than 5 µl/min. Though the mp-Lowdriver can go lower, the SLF3S-0600F flow sensor has a minimal accuracy of +/- 5% or 0.5 µl/min, which is only relevant for flow rates higher than 5 µl/min. The measurements realized at 5 and 10 µl/min show that the accuracy of the flow sensor is the limitation to accurately measure the output flow rates, but the flow accuracy is low enough to address most applications in microfluidics.
Afin de mieux tester les capacités du mp-Lowdriver, nous avons étendu la plage de mesure au-delà de 10 µl/min jusqu'à 50 µl/min. Les résultats sont présentés ci-dessous.
|
mp-Lowdriver |
20 µl/min |
30 µl/min |
40 µl/min |
50 µl/min |
|
Valeur mesurée (µl/min) |
21.04 |
30.57 |
39.99 |
51.21 |
|
Erreur standard |
0.53 |
1.30 |
1.47 |
0.89 |
|
Erreur standard (%) |
2.51 |
4.24 |
3.68 |
1.74 |
Table 3: Comparison between the target and measured values at 20, 30, 40 and 50 µl/min with a mp6-liq, mp-Multiboard and mp-Lowdriver (Bartels Mikrotechnik). Measured with a SLF3S-0600F (Sensirion) thermal flow sensor.
Figure 3: Actual flow rates with a mp6-liq micropump and mp-Lowdriver (Bartels Mikrotechnik) for target flow rates of 20, 30, 40 and 50 µl/min. Measured with a SLF3S-0600F flow sensor (Sensirion)
These results show that the mp-Lowdriver is very suitable for flow rates between 20 and 50 µl/min. Indeed, the error, in all cases, is less than 5% (flow sensor limit).
Nous pouvons donc conclure que le mp-Lowdriver peut être utilisé pour des applications nécessitant des débits supérieurs à 5 µl/min. Des tests supplémentaires devraient être effectués pour les débits inférieurs à 5 µl/min, en utilisant des capteurs de débit plus précis.
Mesures de débit mp-Highdriver
Nous avons effectué 4 mesures (50, 200, 500 et 850 µl/min) pendant quelques secondes afin de tester les capacités du mp-Highdriver pour des débits plus élevés. Les résultats sont présentés ci-dessous.
|
mp-Highdriver |
50 µl/min |
200 µl/min |
500 µl/min |
850 µl/min |
|
Valeur mesurée (µl/min) |
51.62 |
202.86 |
498.09 |
849.35 |
|
Erreur standard |
0.96 |
1.05 |
1.86 |
2.79 |
|
Erreur standard (%) |
1.86 |
0.51 |
0.37 |
0.33 |
Table 4: Comparison between the target and measured values at 50, 200, 500 and 850 µl/min with a mp6-liq, mp-Multiboard and mp-Lowdriver (Bartels Mikrotechnik). Measured with a SLF3S-0600F (Sensirion) thermal flow sensor.
Figure 2: Actual flow rates with a mp6-liq micropump and mp-Highdriver (Bartels Mikrotechnik) for target flow rates of 50, 200, 500 and 850 µl/min. Measured with a SLF3S-0600F flow sensor (Sensirion).
The results for the mp-Highdriver are very satisfactory for the range tested. Indeed, the error, whatever the flow rate tested, is much lower than 2% (below the accuracy limit of the flow sensor) which reveals a very good stability of the device.
When discussing the target value of 50 µl/min measured with both mp-Lowdriver and mp-Highdriver, the results indicate very similar measured values. For this flow rate, the user has a choice between the mp-Lowdriver and the mp-Highdriver.
Conclusion
Bartels Mikrotechnik have created a powerful and easy-to-use environment to control and monitor fluids over a wide range of applications, from millifluidics to microfluidics. Coupled with the mp-Multiboard and a micropump, both mp-Lowdriver and mp-Highdriver offer efficient ways of driving fluids in a microfluidic system, with a good price/accuracy ratio.
Darwin Microfluidics is a worldwide distributor of Bartels products. Find all the components to create your microfluidic setup here!
