Heating system and method
AssigneeLumiraDx UK Ltd.
InventorDavid William Taylor
Life of this patent
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Abstract
A heating system suitable for heating a region of a microfluidic device includes an RC circuit, a DC power supply delivering a constant potential VPS, and a switch system. In use, the heating system alternatingly charges the capacitor of the RC circuit essentially to VPS, e.g., to at least about 0.98×VPS, with a first polarity and then charges the capacitor to essentially VPS with a second polarity opposite the first polarity. During each charging period, the resistor of the RC circuit dissipates an amount of energy essentially given by 0.5×C×(2×VPS)2. The heating system efficiently converts the maximum electrical potential difference generated by the DC power supply (VPS) to thermal energy, i.e., heat.
Claims17
A method of heating at least one of a reaction zone, valve, or gas chamber of a microfluidic strip, comprising:
- positioning a microfluidic strip in an operative position within a diagnostic reader, wherein the microfluidic strip comprises:
- (i) a microfluidic network comprising at least one of a reaction zone, a valve comprising a thermally responsive material, and a gas chamber configured to move liquid within the microfluidic network when the gas therein is heated and (ii) a resistor disposed in thermal communication with at least one of the at least one reaction zone, valve, or gas chamber, wherein the resistor has a resistance R;
- connecting, in series, the resistor and a capacitor disposed on or within the microfluidic strip or within the diagnostic reader to form an RC circuit having first and second RC circuit leads, wherein the capacitor has a capacitance C and the RC circuit has an RC time constant=τRC;
- and
- heating the at least one reaction zone, valve, or gas chamber in thermal communication with the resistor by alternatingly and repeatedly performing the following steps, wherein VPS is an electrical potential between first and second electrical supply leads disposed within the diagnostic reader:
- (1) connecting the first supply lead to the first RC circuit lead and the second supply lead to the second RC circuit lead for a time period τP1 of between about 2 and about 5×τRC, while maintaining the electrical potential of about VPS between the first and second supply leads during the time period τP1;
- and
- (2) connecting the second supply lead to the first RC circuit lead and the first supply lead to the second RC circuit lead for a time period τP2 of between about 2 and about 5×τRC, while maintaining the electrical potential of about VPS between the first and second supply leads during the time period τP2;
- thereby dissipating an average power of about 2×C×(VPS)2/((τP1+τP2)/2) over the resistor.
The method of 1, wherein the thermally responsive material is a wax, an oil, a hydrogel or a thermo-responsive polymer.
A system for heating at least one of a reaction zone, valve, or gas chamber of a microfluidic strip;
- the system comprising an RC circuit, a DC power supply operable to deliver a constant potential VPS, and a switch system;
- wherein the system is configured to carry out the method of any preceding claim.
Dependencies are inferred from the claim text.