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On Pandemic Devices

Shreyas Prakash
7 min
product building

Sterilo is an open-source hardware project where everything ranging from engineering drawings to technical know-hows in building was made transparent.

Version 1.1

Background

Amidst the raging coronavirus pandemic, sterilization of surfaces and common touch points is the key to prevent cross contamination between patients and healthcare workers and to enhance treatment, within isolation wards and Intensive care units (ICU).

Current surface disinfection methods involve spraying Sodium Hypochlorite solution (NaClO) [1] and alcohol wipes, and rinsing after a waiting time of 30 minutes, repeated 3 times a day. These methods are however not effective [2] against many microbes like bacterial spores [3] and in surfaces with high viral loads.

Hence, sterilization is preferred over just disinfection. Even high level disinfectants like 2% glutaraldehyde [4] are ineffective unless exposed for 12 hours. Besides, when the healthcare workers directly come in contact (touch) with these infected surfaces while treating patients, they become carriers of infection, leading to a higher risk of COVID-19 transmission [5] within the isolation ward /ICU.

On the other hand, autoclaves are the gold standard in sterilizing smaller instruments used in ICUs and Isolation wards. Each autoclave cycle takes 30 minutes while the drying process takes an hour to remove steam residue on the instruments. However, a surge in coronavirus patients in a given hospital might lead to exceeding the capacity of autoclaves.

There are other disinfection methods such as Fumigation, which uses high level disinfectants like Formaldehyde [7] and Glutaraldehyde [8,9]. This method requires 10 hours of exposure time [10] and another 24 hours for the fumes to be ventilated, after fumigation is carried out in a room.

However, currently in many of the Indian government hospitals, the operations resume 30 minutes, that too in poorly ventilated rooms after the fumigation which renders healthcare workers exposed to its harmful fumes. Harmful effects [11,12] include mucous membrane irritation, pulmonary symptoms, Epistaxis, allergic contact dermatitis, asthma.

Ultraviolet radiation is an effective sterilization method, commonly found in Biosafety cabinets. The spectrum between 254nm to 265nm usually called UV-C has the maximum germicidal effect.[13] However, this method is currently not used in hospitals due to its harmful effects to human beings on exposure like skin cancer and eye damage [14].

Existing UVC Sterilizer robots [15] and trolley models [16] that are being introduced in the market to sterilize isolation wards require the people in the ward to vacate the ward while it sterilizes, since it places patients at risk of exposure to UVC radiation. But vacating is not logistically feasible, especially in Indian government hospitals. Hence the main need is to effectively sterilize frequently touched surfaces without causing harmful effects to patients and healthcare workers.

Need

Surfaces

Effective sterilization methods for fixed touch points (surfaces) within isolation wards and ICUs.

Complement autoclaves

Supplementary sterilization for instruments, in addition to autoclaves, to reduce their overuse.

Need for reuse of Personal protective equipment

Reuse of N-95 respirators for non-medical staff so that it is available to medical staff working in high viral loads like in isolation wards and ICUs.

Solution

Sterilo, a portable surface sterilizer that uses UV-C radiation to sterilize common touch points within ICUs and isolation wards, even while the patient is present in its proximity and no special shielding is required. Safety features have been incorporated to avoid accidental exposure to UVC radiation, such that only when it's clamped onto the surface, the UV lamps turn ON.

Sterilo can be used in two configurations:

Clamped onto surfaces

It features suction cups that clamp onto any surface. (See picture below). Once turned ON, the sterilization process runs for 20 minutes and turns off automatically with a beep, so that the user can unclamp it and place it on the next surface.

Box type

where a lid with an additional UV-C lamp is placed over configuration A. It is designed to hold most small instruments (for compatibility list see below). A removable mesh holds the instruments in place, while two UV-C lamps below ensures all surfaces of an object are completely exposed.

It is designed to sterilise most of the common touch points within isolation wards and ICUs in hospitals which includes buttons of vital monitors, ventilators, breathing units, pulse oximeters, contact thermometers, N95 masks, other touchpoints such as door handles, plugs, sockets, buttons of control units such as portable X-ray machines, echo machine controls for cardiac patients etc and even surgical equipments such as scissors, shears and tongs. The product is aimed at hospitals, makeshift wards and testing labs.

Helps sterilise the following categories of objects:

Main Features

How to replicate

Detailed assembly instructions were made open source to help other builders and makers all over the globe participate in building effective products for the pandemic.

See Assembly Instructions

References

Experts

Interviews conducted with the following experts during the design process

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