Chip calorimeter

Keywords Multi-analyte biosensor Microelectrode-array Enzyme immobilization Enzyme stability Differential scanning calorimetry (DSC) Chip-calorimeter... 

Obviously, for LPE and the ethylene-propylene copolymer much higher heating rates are needed to avoid or even hinder reorganization. Therefore, experiments at extremely high rates have been carried out using a thin-film (chip) calorimeter or nanocalorimeter, see also next section. 

Figure 4. The present evolution of Standard DSC towards a range of low- to high-speed calorimeters [32]. Commercial instruments like heat-flux and power-compensation Standard DSCs work typically at scan rates of 0.1 to 60 C/min High Performance DSC (HPer DSC), using a modified PerkinElmer power-compensation Pyris 1 or Diamond DSC, covers the range 0.1 to 500 C/min thin-film (chip) calorimeters have scan rates from 1000 to 1.2-10 C/min and rates as high as 6-10 C/min are attainable using the high-speed pulse-calorimeter (all numbers are approximate indications).

Huth H, Minakov AA, Serghei A, Kremer F, Schick C (2007) Differential ac-chip calorimeter for glass transition measurements in ultra thin polymeric films. Euro Phys J Special Topics 141 153-160... 

Winter W, Hohne WH (2003) Chip-calorimeter for Small Samples. Thermochim. Acta... 

Figure 13.1. Thin-film chip calorimeter based on the thermal conductivity gauge TCG 3880. Scheme (a) and micro-photograph of the frame and the membrane loaded with a sample (b). [Adapted, by permission, from Ray, V V Banthia, A K Schick, C, Polymer, 48, 2404-14, 2007.1...

A commercial version of the chip calorimeter with an 18 pi flow cell is available from TTP Labtech. 

The construction principles of such chip calorimeters are similar to those of conventional calorimeters The heater corresponds to the furnace, and the center of the membrane corresponds to the calorimeter system, including the sample container. The thin membrane serves as the thermal path between the heater and the sample with very low thermal resistance and very low effective heat capacity. The thermopile measures the temperature difference between the sample site and the chip frame (surroundings). Because of the much larger lateral dimension of the membrane of at least two orders of magnitude, the heat exchange between the sample and the frame can be neglected. The chip calorimeter can therefore be considered a quasi-adiabatic calorimeter when vacuum is applied. 

Lai et al. (1997) fabricated a chip calorimeter with a 100 nm thick Si-N membrane with two Ni thin-film stripes (30 nm thick and 0.4 mm wide) as the differential heater pair, one serves as the sample heater and the other as the reference heater. With two synchronized electrical current pulses, the two heaters can be heated up to 300 °C at a rate of about 30000Ks. The heater stripes also function as temperature sensors. The apparent heat capacity of the chip is about 6 x 10 J at 300 K and the lowest detectable heat is given as 0.2 nj. 

Differential alternating current chip calorimeter for in situ investigation of vapor-deposited thin films. Rev. Sci. Instrum., S3, 033902. 

Hdhne, G.W.H. and Winter, W. (2005) About models and methods to describe chip-calorimeters and determine sample properties from the measured signal. Thermochim. Acta, 432,169-176. 

Huth, H., Mlnakov, A.A., Schick, C. Differential ac-chip calorimeter for glass transition measurements in ultrathin films. J. Polym. Sci. Pt. B-Polym. Phys. 44(20), 2996-3005 (2006)... 

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