An Open-Source Neonatal Phototherapy Device

Abstract

Severe neonatal hyperbilirubinemia (SNH) (jaundice) is responsible for over 114,000 preventable neonatal deaths annually, as the technology that can treat the condition is cost-prohibitive for low- and middle-income countries. In this study an open-source neonatal phototherapy device (NPTD) to treat SNH was designed, built, and validated against the phototherapy technical specifications set by the American Academy of Pediatrics and UNICEF. The open-source device can be built for a tenth of the cost of the least expensive proprietary one on the market, with treatment metrics equivalent to or exceeding commercial devices available in developed nations. This device, whose material costs are USD 93.00, was shown to deliver an irradiance up to 80 µW/cm²/nm, within the acceptable wavelength range of 420–500 nm. It was further demonstrated that the unit could deliver a uniform distribution of irradiance (34.5 ± 4.3 µW/cm²/nm) over a surface area exceeding 3200 cm². These findings show that the open-source NPTD is capable of delivering accurate, consistent, and reliable irradiances for the management of SNH. By releasing full documentation in an open-source manner, the device may be broadly used to ensure affordable and consistent low-cost means of improving the quality of care for SNH.

1. Introduction

Severe neonatal hyperbilirubinemia (SNH), or jaundice, is responsible for an estimated 114,100 neonatal deaths annually [1]. Another 75,000 newborns survive, yet they may develop kernicterus spectrum disorder (KSD) for the remainder of their lives [2]—a chronic condition characterized by motor dysfunction and oculomotor and auditory impairments [3]. The majority of these cases occur in low- and middle-income countries (LMICs), particularly in Sub-Saharan Africa, South Asia, and the Eastern Mediterranean [4]. A systematic review and meta–analysis by Slusher et al. [5] concluded that high-income countries have an incidence rate of SNH of 3.7 per 10,000, while LMICs have an incidence rate of 244.1 per 10,000. This disparity represents the highly treatable nature of SNH [6] if access to technology, resources, and training is provided [7]. Current devices used for treating SNH (

Table 1. Market analysis of common neonatal photo therapy devices (NPTDs) used in North America.

Device	Cost (CAD)	Ref.
NEOBLUE OVERHEAD W/ROLLSTAND	11,685.00	[8]
NEOBLUE COMPACT LED PHOTOTHERAPY SYSTEM	4315.00	[9]
Pocket Nurse Infant Phototherapy Unit	2046.02	[10]
Bistos BT-400 Neonatal Blue LED Phototherapy Equipment	1265.39	[11]
Bistos BT-550 Infant Warmer w/LCD Display	6481.13	[12]

) are manufactured in high-income countries and intended to serve a high-income consumer base, where sales margins are highest.

Thus the devices are not only cost-prohibitive in LMICs, but repairing these devices is challenging [13] and may lead to ‘medical equipment graveyards’ [14].

One way to overcome this challenge is the design and digital-distributed manufacturing of open-source medical devices [15,16], which was somewhat normalized in response to the COVID-19 pandemic [17]. The best practice for open hardware [18,19] involves designing hardware that can be easily replicated in a wide range of low-cost digital manufacturing tools like open-source RepRap-class 3-D printers [20,21], open-source autoinjectors [22], open-source cell culture incubators [23], and open-source microscopes [24]. This has been shown to produce high-quality medical and scientific hardware for a small fraction of the cost of proprietary products [25,26].

Treatment for SNH is most commonly administered through phototherapy [27,28] by exposing an infant to a light source of sufficient intensity (irradiance ≥ 30 µW/cm²/nm) [29] and appropriate wavelength (420–500 nm) [30] to photoconvert excess bilirubin into excretable photoproducts [31]. The use of exchange transfusion carries additional risks such as infection, blood clots, and mortality and produces less effective patient outcomes [32]. Intravenous immunoglobulin administration poses several concerns given its low efficacy, higher cost, and donor requirements [33]. Phototherapy is the preferred method of treatment [34]. This paper uses the open-hardware model to develop a low-cost NPTD capable of being manufactured in LMICs. In conjunction with an open-source validated irradiance meter [35] which, when paired with the phototherapy device, creates a system to effectively treat SNH at minimal cost.

This study validated the performance of the device by measuring its output wavelength, intensity, and coverage, and compared those values with the standard set by the American Academy of Pediatrics (AAP) and UNICEF phototherapy technical specifications [36]. A further cost and performance analysis was also made against modern commercial units sold in North America [37]. The results from deployment and testing at Kenyetta University, Kenya, are presented and discussed in the context of providing low-cost phototherapy everywhere in the world.

2. Materials and Methods

A fully assembled open-source NPTD is shown in Figure 1 and was constructed in three sub-assemblies:

(a)

The structural body including the 3D-printed electronic housings, PVC pipes, and joints connecting the pipes.

(b)

The microprocessor, power delivery, and interface electronics.

(c)

The light source and heat dissipation assembly.

The detailed assembly of the open-source NPTD is presented in Appendix B. A calibrated Ocean Insight UV-VIS FLAME spectrometer (Ocean Insight, Orlando, FL, USA) [38] was used to measure both the intensity and peak wavelength over the range of 200–800 nm. Multiple readings over a 2 h time span were taken to verify consistent spectral output. A mapping of the illuminated surface was created by holding the source at distances of 33 and 45 cm and measuring irradiance at equally spaced intervals of 10 cm.

The intensity, wavelength, and irradiated surface area were then compared with the standard set by the AAP for effective phototherapy treatment for SNH [27,28] and commercial products currently in use. The UNICEF phototherapy technical specifications [36] were used to determine if the device offered all the required functionalities for hospital operation. Finally, a bill of materials (BOM) was developed (Appendix A) to determine the cost compared with commercial units available in North America.

3. Results

3.1. Spectral Analyses

A calibrated Ocean Insight spectrometer was placed 33 cm below the neonatal lamp. A distinct peak of 80 µW/cm²/nm at 459 nm is shown in Figure 2. The total bandwidth is 420–500 nm, with a half-power bandwidth of 22 nm. The performance of the open-source NPTD is comparable to that of the commercial devices (

Table 2. Common commercial NPTDs, adapted from V. Bhutani et al. [25], compared with FAST NLTD.

	Device	Distance to Patient (cm)	Footprint Area (Length × Width, cm2)	Spectrum, Total (nm)	Bandwidth (nm)	Peak (nm)	Footprint Irradiance (μW/cm2/nm) Max
							Min	Max	Mean ± SD
LED	neoBLUE	30	1152 (48 × 24)	420–540	20	462	12	37	30 ± 7
	PortaBed	≥5	1740 (30 × 58)	425–540	27	463	14	70	67 ± 8
	FAST NPTD	30–45	3600 (60 × 54)	420–500	22	459	23.9	43	35 ± 4
Fluorescent	BiliLITE CW/BB	45	2928 (48 × 61)	380–720	68	578	6	10	10 ± 1
	BiliLITE BB	45	2928 (48 × 61)	400–550	55	437	11	17	17 ± 2
	BiliLITE TL52	45	2928 (48 × 61)	400–550	35	437	8	13	13 ± 2
	BiliBed	0	693 (21 × 33)	400–580	80	450	4	8	8 ± 2
Halogen	MiniBiliite	45	490 (25 diam)	350–800	190	500	<1	3	3 ± 1
	Phototherapy Lite	45	490 (25 diam)	370–850	200	590	<1	17	7 ± 5

). No variation in irradiance was observed over the 2 h period in which the test was conducted. A 2 h test period was determined to be sufficient given the stability of LEDs over long periods of time [39].

3.2. Irradiance Footprint

Figure 3 illustrates the light distribution when the source is placed 45 cm above the bed. The location of the lamp head is represented by the hatched gray box. It is observed that the distribution of the light was relatively uniform and that 81% of the surface is exposed to the minimum recommended dose for SNH of 30 µW/cm²/nm [29,30,31,40,41,42]. The total surface area mapped was 3240 cm². The mean distribution of irradiance was 34.5 ± 4.3 µW/cm²/nm, as shown in Figure 3.

Figure 4 and Figure 5 illustrate mappings using the calibrated Ocean Insight spectrometer and the open-source FAST irradiance meter, respectively. The hatched gray rectangle represents the location of the light source, and the right-hand gradient indicates the intensity of the light in µW/cm²/nm. Measurements were taken at 10 cm intervals for a crib area of 3600 cm² and a distance from the source of 33 cm.

The irradiance mapping using the Ocean Insight spectrometer (Figure 4) showed a mean of 54.8 ± 12.0 µW/cm²/nm, while measurements taken using the FAST irradiance meter (Figure 5) showed a mean of 55.1 ± 11.8 µW/cm²/nm. The absolute mean difference in measured values between the two devices was 0.88 µW/cm²/nm.

Table 2 summarizes parameters of commercial therapy units originally listed in the AAP technical report on phototherapy to prevent severe neonatal hyperbilirubinemia [27,28]. The parameters of the NPTD are also included for comparison.

Table 1 shows the cost of typical commercial devices in use in North America. The products selected for market analysis were chosen based on similarity to the NPTD; specifically, they are all overhead light emitting diode (LED) devices. As shown in Appendix A, the cost of building the developed NPTD in Canada is CAD 130.03, or USD 92.93. The cost of this NPTD is one tenth the cost of the least expensive proprietary commercial option on the market.

Irradiance measurements were taken from the NPTD by the two light meters, as shown in

Table 3. Light meter comparison.

Distance from Light (cm)	3D-Printed Light Meter (µW/cm2/nm)	MTTS Light Meter (µW/cm2/nm)
10	34.28	35
15	17.64	21
20	13.11	14
25	10.40	10
30	9.60	7
40	4.68	4
50	3.26	3
60	2.65	2

. It should be pointed out that there was minimal variance recorded between each mapping, suggesting sufficient accuracy and the reliability of the locally assembled devices (both the open-source NPTD and the locally fabricated 3D-printed open-source FAST light meter) with reference to the established reference devices.

4. Discussion

Phototherapy is the primary treatment for SNH [42], utilizing light with an irradiance of at least 30 µW/cm²/nm and a wavelength range of 420–500 nm [40] to facilitate the breakdown of excess bilirubin in the blood [41].

High-income countries experience far lower rates of SNH compared with LMICs, where there is limited access to necessary equipment [5]. As a result LMICs are disproportionately affected by kernicterus spectrum disorder (KSD) [43], a preventable chronic disease characterized by abnormal motor function, oculomotor impairment, and auditory complications [44]. KSD is caused by the buildup of bilirubin in the neonate’s blood and requires immediate phototherapy to lower the level of bilirubin [45]. KSD severely limits the abilities and opportunities of those afflicted for the remainder of their lives [43]. This paper has shown that construction of appropriate and cost-effective phototherapy equipment can be implemented through open-source hardware to effectively treat SNH in LMICs.

Spectroscopic analysis showed that the NPTD emitted a light at a wavelength of 460 nm with half-power bandwidth of 22 nm. This falls within the spectrum shown to effectively photodegrade bilirubin as cited by Porter [46] and Maisels [47]. At a distance of 45 cm from the NPTD, the mean irradiance was 34.5 ± 4.3 µW/cm²/nm, which compares well with the commercial products presented in Table 1 [27].

The total illuminated surface area available for therapy is 3600 cm², which exceeds UNICEF’s required technical specifications [36] of a minimum effective surface area ≥ 1220 cm². It also exceeds the area of commercial devices referred to in Table 2 [27]. Several infants are sometimes placed together to receive phototherapy in LMICs, which may lead to overcrowded cribs [48]. The larger effective area provided by the open-source NPTD may reduce the risk of overcrowding cribs.

The total material cost to construct these developed NPTDs is USD 93.00 (CAD 130.00), which represents a 92.3% to 98.7% cost reduction compared with commercial devices. In LMICs, access to effective treatment of SNH has not only been hindered by high costs, but also by technologies that are ill-suited to these resource-limited settings [49]. This NPTD significantly lowers this financial barrier.

Another limitation to effective treatment is the inability to consistently monitor the irradiance of delivered phototherapy [6]. It has also been demonstrated that the open-source FAST irradiance meter [35] is equally effective at measuring irradiance as a calibrated spectrometer, with an absolute mean difference of less than 1 µW/cm²/nm. The NPTD in conjunction with the FAST irradiance meter establishes an open-source system to treat SNH at a price point significantly lower than that a set of commercial equipment.

Further device refinements should be explored, such as incorporation of reflective material to increase irradiance homogeneity [50], evaluation of long-term operation of the device, increasing power delivery, and installation of multiple LED lamps per unit. Clinical validation will be required before the device can be approved for clinical use. In addition to regulatory requirements, testing within a clinical context will also inform further developments to improve device durability and maintenance feasibility and provide feedback for changes to the user interface. No tests involving humans or animals have been conducted. The NPTD meets most of the UNICEF-required technical specifications [36], with the exception of the following: battery operation for power outages less than 10 min and the incorporation of white LED lamps for examination. These are considered lower-priority features and will add cost and not improve patient outcomes.

5. Conclusions

One of the leading causes of severe neonatal hyperbilirubinemia in LMICs is the lack of cost-effective and appropriate technology to prevent the condition. It has been demonstrated that an open-source NPTD to effectively treat SNH can be built at a significantly lower cost while producing treatment metrics equivalent to or exceeding commercial devices available in developed nations. The developed device, whose material costs are USD 93.00 (CAD 130.00), was shown to produce an irradiance of 80 µW/cm²/nm within the acceptable range of 420–500 nm. It was further demonstrated that the unit could produce a uniform distribution of (34.5 ± 4.3) µW/cm²/nm over a surface area exceeding 3200 cm². The device has been shown to meet or exceed commercial device parameters and has been tested in a LMIC context at the University of Kenyetta, Kenya; however, it requires clinical certification and regulatory testing before clinical deployment. By releasing documentation, building instructions, and design in an open-source manner, the device may be broadly distributed. In conjunction with the open-source irradiance meter, the pair is technically validated, pending clinical validation, to treat SNH in resource-limited communities.