A sensitive thermochemical detector with a new target droplet supply and immobilization process

Abstract

A thermal detector structure of bio-thermochemical sensor with a new target droplet supply is considered, analyzed and developed. The basic structure of the bio-thermochemical sensor is a Pt film microbolometer thermally insulated from a silicon thermal conductor substrate to enhance the temperature sensitivity. In the detector structure, it is calculated from a finite element analysis that the variation in lateral size of immobilized droplet, larger than detector film size of 50 μm, affects little on the temperature change, while the real vertical size of the droplet keeps nearly the same as around 70 μm. These indicate the validity of formation of the target droplet onto the detector part as an accurate thermal measurement. Based on this, a new supplying and immobilizing process of the droplet is developed to realize a soft formation of the droplet on the detector surface with retained intact immobilization of liposome at least for 24 h, not giving the membrane a mechanical stress and destruction. Thereafter, we have evaluated a bio-thermochemical reaction in a droplet of mixed solution of 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) liposome and lysozyme by the newly developed thermochemical sensor. Some new peaks in thermal spectra were observed for the case of the mixture, which were not found so far in the case of each single solution of liposome or lysozyme, indicating that their bio-thermochemical interactions were newly detected in this method. It was also found that the thermal sensor with new forming process of droplet target detects the thermochemical reaction of respective DPPC liposome and lysozyme, consistent with the same as those reported by a differential scanning calorimetry.