Digitally-controlled array of solid-state microcoolers for use in surgery

Abstract

This paper presents an approach for generating a well-defined cooling pattern over an area of tissue. An array of solid-state microcoolers is used, which could be included in a probe that provides local cooling. This medical instrument can be used for removal of scar tissue in the eye or for the rapid stopping of bleeding due to micro-cuts, which makes it a useful tool to medical doctors and could make surgery more secure to the patient. The array of microcoolers is composed of 64 independent thermo-electric elements, each controlled using an integrated circuit designed in CMOS. The independent control allows the flexible programming of the surface temperature profile. This type of control is very suitable in case abrupt temperature steps should be avoided. Cooling by lateral heat flow was selected in order to minimize the influence of heat by dissipation from the electronic circuits. Moreover, a thermo-electric component with lateral heat allows fabrication of the cooling elements using planar thin-film technology, lithography and wet etching on top of the silicon wafer. This approach is potentially CMOS compatible, which would allow for the fabrication of the thermo-electric elements on top of a pre-fabricated CMOS wafer as a post-process step. Each pixel is composed of thin-films of n-type bismuth telluride, Bi 2 Te 3 and p-type antimony telluride, Sb 2 Te 3 , which are electrically interconnected as thermocouple. These materials have excellent thermoelectric characteristics, such as thermoelectric figures-of-merit, ZT, at room temperatures of 0.84 and 0.5, respectively, which is equivalent to power-factors, PF, of 3.62 9 10 -3 W K -1 m -2 and 2.81 9 10 -3 W K -1 m -2 , respectively. The theoretical study presented here demonstrates a cooling capability of 15°C at room temperature (300 K & 27°C). This cooling performance is sufficient to maintain a local tissue temperature at 25°C, which makes it suitable for the intended application. A first prototype was successfully fabricated to demonstrate the concept.

Multilayered structure and enhanced thermoelectric properties of Bi1.5 Sb0.5 Te3 film with preferential growth

“…The ZT value is also higher than the reported results of the Sb 2 Te 3 and Bi 2 Te 3 -based materials [13,15,[19][20][21][22][23][24]. We consider that this enhancement in ZT is attributed to the lower thermal conductivity and higher power factor of the multilayered Bi 1.5 Sb 0.5 Te 3 film, owing to this multilayered structure.…”

Local Evolution of the Elastocaloric Effect in TiNi-Based Films

“…In contrast to other caloric effects relying on high magnetic or electric fields [1,2,7], the driving force for elastocaloric cooling is mechanical stress or strain. This approach is highly attractive for miniature cooling applications, such as active cooling in microelectronics, bio-medicine, and chemical analytics, e.g., local cooling of biological tissue, rapid blood cooling in microsurgery, temperature stabilization of lab-on-chip systems [8,9]. The high surface-tovolume ratio inherent to films is in this regard advantageous, since it promises large heat transfer rates and, concomitant, high cycling frequencies.…”

Synergistic Optimization of the Thermoelectric and Mechanical Properties of Large-Size Homogeneous Bi0.5Sb1.5Te3 Bulk Samples via Carrier Engineering for Efficient Energy Harvesting

“…Bismuth–antimony–telluride-based alloys are well-known candidates for excellent thermoelectric conversion at room temperature. Therefore, they have been materialized in refrigerators and power generators. , Most of the commercial thermoelectric legs utilized for the module manufacturing are mainly fabricated by the zone melting (ZM) method, , and they exhibited a ZT of around unity. Meanwhile, the mechanical strength of the single-crystalline materials is low due to their intrinsic brittleness, which makes it difficult to cut with micron-sized legs and assemble TE modules.…”