The E-Field-UV Air Purifier: A Low-cost Air Purifier

An air purifier uses electric fields & ultraviolet to kill harmful airborne microorganisms

Specifications

PowerPC Power supply unit; High voltage generator
UV light source9W UV lamp
Wire mesh networkMaterial: Stainless steel
Size: 10 x 10 cm
Radial electric fieldMaterial: PVC
Type: T-socket
Diameter: 10 cm
Air Flow Rate0.188m3s-1
Residence Time in Each Chambers
Parallel Chamber0.042s
Perpendicular Chamber0.042s
Radial Chamber0.0229s
Neat anaerobic plate count6.64 x 108 CFU/mL
Mean Colony count after deviceNeat: 210
10-1: 140
10-2: 75
10-3: 10

Overview

This tech spec was submitted by Ruwan Jayakantha as part of the University Technology Exposure Program.


This air purifier uses two methods to kill microorganisms in the air: UltraViolet light and High Electric Fields (2000 kV m-1). Hence the name UV-assisted Multi-electric Field Air Purifier. 

Problem / Solution

One of the significant threats to human health is the harmful microorganisms that are transferred and suspended everywhere. Using chemicals such as alcohol to eliminate harmful microorganisms has disadvantages that limit its use. Microorganisms are selectively and slowly eliminated through chemical means. Aside from being unfavorable to the environment, chemicals are often limited to surfaces and are less effective against airborne microorganisms. Air purifiers have grown in popularity over the pandemic, but conventional air purifiers suffer from high cost, high energy consumption, and filler replacement issues.

The E-Field/UV Air Purifier is a simple and low-cost air purifier that combines UV light and a direct voltage electric field to kill microorganisms in the air effectively. The strong multi-directional electric field kills the microorganisms effectively by sucking up the air in the enclosed area and letting the clean air flow out. The device is effective against high bacterial concentrations in closed rooms and is compatible with any air conditioner machine.

Design

The air purifier is an upright box with the airflow inlet at the bottom and a clean air outlet through a pipe in front. The design comprises three parts: wire meshes for the electric field, a lamp for UV light, and a blower for air uptake.

The high electric field is divided into three main chambers to kill the microbes more efficiently: the parallel electric field, the perpendicular electric field, and the radial electric field. The parallel and perpendicular fields are created using two mesh networks, while the radial electric field is made using a cylindrical type mesh network inside a PVC tube. These mesh networks have a high charge density to attract charged organisms more.

A blower at the middle of the device uptakes the air from the environment through the inlet at the bottom. The air is directed to pass through the first of the three electric chambers: the parallel electric field. This chamber directs the airflow parallel to the electric field with three wire mesh networks. The wire mesh has a positive, negative, and positive charge, respectively, from bottom to top.

The air from the first electric field passes through the blower and then is directed to the ultraviolet chamber. After going through the UV chamber, the air flows through the second electric chamber: the perpendicular electric field. This chamber directs the airflow perpendicular to the electric field between the two wire mesh networks. The bottom wire mesh is negatively charged, while the top wire mesh is positively charged.

After flowing through the second electric field, the air goes inside the PVC tube with the third electric chamber: the radial electric field. This chamber directs airflow radially to the electric field. The air that exits through the PVC outlet is considered clean air.

The device noticeably reduced the bacteria (Staphylococcus aureus) in the airflow. The neat plate count of 6.64 x 108 CFU/mL was reduced to a mean bacterial colony count of 210 after passing through the air purifier.

References

A research paper describing the challenge, design, and outcome of the research.

D.N.P. Ruwan Jayakantha, H.M.N. Bandara, Nadeesha M. Gunawardana, R.P.V. Jayantha Rajapakse, Dulari S. Thilakarathne , Elisabetta Cominib, Nanda Gunawardhana , S.M.M.L. Karunarathn

Wevolver 2023