A modified continuous flow microcalorimeter for measuring heat dissipation by mammalian cells in batch culture

Microcalorimeters to monitor the heat dissipation of bench-scale animal cell cultures on line and in real time require a continuous circuit between the vessel measuring heat flow rate and the bioreactor. The modifications to the transmission lines and calorimetric heat exchanger were to: (i) reverse the usual upward direction of the cell suspension in the flow vessel to downwards; (ii) install an in situ washing/cleaning facility; (iii) use low diffusivity PEEK material; and (iv) maintain thermal equilibration by water-jacketing the transmission tubing. Chemical calibration showed that there was more than a 20% difference between the physical volume and the effective thermal volume. An appropriate thermodynamic system was defined in order to permit enthalpy balance studies.We are indebted to the BBSR.C (UK) for financial support under grant No. 2/3680. Mr. R.L. Taylor (ThermoMetric Ltd, Northwich, Cheshire) has been extremely helpful in discussions about the various designs.