A cost-effective homogenous, composite material provides sustained heat at a desired temperature for point-of-care diagnostics and other applications.
Point-of-care (POC) diagnostic tests have the potential to greatly enhance patient care and accessibility by reducing the time and equipment necessary for testing. Many current POC tests require 30-40 minutes of stable temperatures which, in turn, requires expensive and complex heating platforms that limit wide-scale use of POC tests. A reliable, safe heat-source that maintains fixed temperature would enable low cost, disposable devices for the biochemical reactions necessary for testing.
The heat-source composite material developed in the Bau Laboratory can achieve a range of high temperatures required for many POC tests. These temperatures can be sustained for upwards of 40 minutes, and the POC reaction can occur within something as common as a Styrofoam cup. The material can be engineered to achieve separate temperature plateaus or to sustain a desired temperature for a specified period.
Commercially available exothermic materials provide portable heat sources, for example for hand warmers and meals ready-to-eat. However, these materials lack the temperature regulation needed for POC test protocols. Although phase change materials(PCM) have been usedbefore to stabilize temperatures, they were separated from the heat source, slowing ramp uptimes. The homogenous combination of exothermic material and PCM material providesrapidheating andcan be engineered to support sophisticated heating protocols for biochemical reactionssuch as those needed for two stage amplification (i.e.,
16-7708).Other applications may include electricity-free, self-heating, temperature-regulating blankets, garments, packages, and shelters.
Top Image: Schematic ofpotential material application. POC test tube samples are supported by a holder and immersed in the composite material (bronze). The material provides heat for a colorimetric biochemical reaction that differentiates positive samples (P, +, yellow) from negative samples (N, -, red)
Bottom Chart: Vial’s temperature curve and POC test reaction schematic. Upon addition of water, the composite material temperature quickly rises to an equilibrium temperature between 60-65⁰C. This range of temperature is optimal for loop-mediated isothermal amplification (LAMP) reactions, a common molecular POC test method. These optimal temperatures are maintained upwards of 40 minutesindependent of ambient temperatures. An example testing setup involves a POC sample immersed in the composite material and contained within a Styrofoam cup (inset).