Temperature control

Our temperature control modules are designed to allow for accurate and rapid temperature regulation ranging from 10-42°C with high precision and accuracy of ±0.5°C.

Concept and design

Temperature measurement and feedback are taken directly from the bed-of-nails (BON) beneath measurement sites.

Temperature regulation is performed using circulating water in the BON. It is not a straightforward engineering task to integrate liquid flow in the BON; however, temperature control must be performed very close to the measurement sites to ensure precise control with minimum fluctuations. If not, laboratory and cabinet temperature will influence the accuracy significantly.

For QPatch, the manifold base plate is also thermostated with water from the same reservoir, ensuring that the manifold has the same temperature as the BON decrease time to equilibrium.

QPatch II temperature control specifications

QPatch II temperature control specifications

QPatch II temperature control schematics

Schematics of QPatch II temperature control. Both BON and manifold landing plate are temperature controlled to allow for fast equilibrium. Temperature sensors are embedded in the BON, directly below the measurement sites, with feedback to circulating unit and internal PC. Data are logged on the Oracle database with timestamps together with rest of the patch-clamp data.

Data storage

Data is registered and stored in the database together with electrophysiology data. Temperature data is thus readily available for analysis after a run.

Water and electronics

“Why have you decided to use water?” is a question we have received several times. Water is an efficient heat conductor, and the liquid flow gives us the best possible solution to regulate temperature close to the measurement sites efficiently. The solution is ISO-certified for electrical safety.

Accuracy and precision

The design allows for a stable BON temperature independent of room temperature. For QPatch, the temperature span is as little as ±0.1°C and uniformity across the QPlate of  ±0.2°C (at 10-30°C) and ±0.4°C at temperatures above 30°C. Accuracy is ±0.5°C from the target temperature for all sites. This is due to an excellent heat coupling between BON and QPlate, with a coupling efficiency of 0.93.

Thermal measurements of BON temperature for QPatch II 48.

Thermal measurements of BON temperature for QPatch II 48.

Temporal variation

The measurement plates stabilize temperature within 2 min and are thus well equilibrated after priming has been done.

When plates have equilibrated, variation in temperature over time is low. Temperature fluctuations over time are ±0.2°C and thus negligible.

The figure displays set temperatures and ramping temperatures for 10, 18, 26, 34 and 42°C when used in a laboratory environment of 24°C. The BON temperature measurement displays stable temperatures (+/-0.5°C) for all set temperatures, and the temperature is measured at the BON just below the measurement sites.

Instrument variation

Instrument-to-instrument variation can be critical when having multiple instruments on the same or several sites. The most significant difference we have found during validation  (QPatch II 16 and QPatch II 48) was ±0.25°C which is within user requirement specifications and does not affect pharmacology data.

No significant difference was observed between the two systems' pharmacological data. Group Hill fits on QPatch 301 vs QPatch 313. Dose-response curve recorded on a QPatch II 16 and a QPatch II 48 with temperature control. 15°C (left), 25°C (middle) and 35°C (right).

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