2026 Undergraduate Research Showcase

Cooling the Fourth State of Matter

Document Type

Student Presentation

Presentation Date

4-24-2026

Faculty Sponsor

Dr. Jim Browning and Dr. Marcus Pearlman

Abstract

Cold atmospheric-pressure plasma (CAP) has significant potential for sterilization in medical and agricultural applications because it can inactivate bacteria and remove biofilms without the use of harsh chemical disinfectants. Plasma is often referred to as the fourth state of matter and forms when sufficient energy is added to a gas. This causes partial ionization and produces a mixture of ions, electrons, and neutral particles. In CAP devices, a time-varying high voltage applied across electrodes ionizes the surrounding gas, generating reactive species capable of destroying microorganisms. One method for producing CAP utilizes low-temperature co-fired ceramics (LTCC), a multilayer glass-ceramic material commonly used in microelectronic devices. However, prolonged operation of these devices can lead to excessive heat generation, which may damage structural components and raise surface temperatures. This heating is undesirable because it may contribute to bacterial inactivation independently of the plasma, making it difficult to isolate the true sterilization effectiveness of the CAP device. To address this issue, a copper heat-sink structure, made using copper plating and tubing, integrated with an active water-cooling system was designed to remove heat from critical regions of the plasma device. Copper was selected for its high thermal conductivity, enabling efficient heat transfer away from the plasma generation region. Chilled water from an external chiller is circulated through copper tubing to maintain lower operating temperatures. Another method being investigated is the use of duty cycling, where the device is periodically turned on and off rather than operated continuously. By limiting the amount of time the plasma is active, the device is allowed to cool between operating intervals, which helps reduce overall thermal buildup. Adjusting the duty cycle can therefore provide a balance between maintaining effective plasma generation, preventing excessive heating of the device components, and surrounding surfaces. The cooling processes are evaluated using thermal imaging, temperature measurements, and operational testing to assess its effectiveness in reducing thermal buildup. By controlling device temperature, this system enables longer and more stable operation while ensuring that microbial inactivation is primarily driven by plasma rather than excess heat.

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