Patent Application
20170102346
The present application is directed to a MEMS cassette for insertion into a DSC calorimeter and a DSC calorimeter using MEMS cassettes to conduct DSC experiments.
Bio-molecular research is often performed by using Differential scanning calorimetry or DSC. DSC is a label-free thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature throughout an experiment and the difference in the amount of heat required is measured by using a sensing device.
For testing the stability of proteins, for example, DSC is used to characterize the stability of a protein or other biomolecule directly in its native form. It does this by measuring the heat change associated with the molecule's thermal denaturation when heated at a constant rate.
For proteins, a biomolecule in solution is in equilibrium between its native (folded) and denatured (unfolded) conformations. The higher the thermal transition midpoint (Tm), the more stable the molecule. DSC measures the enthalpy (H) of unfolding that results from heat-induced denaturation. It is also used to determine the change in heat capacity (ΔCp) of denaturation. DSC can elucidate the factors that contribute to the folding and stability of native biomolecules. These include hydrophobic interactions, hydrogen bonding, conformational entropy and the physical environment. The precise and high quality data obtained from DSC provides vital information on protein stability in process development, and in the formulation of potential therapeutic candidates.
The DSC technique is widely used across a range of applications, both as a routine quality test and as a research tool. DSC may be used to study oxidation, chemical reactions and phase changes in a sample or sample solution.
Typical information that can be derived from DSC measurements includes: characteristic temperatures (melting, crystallization, polymorphous transitions, reactions, glass transition), melting, crystallization, transformation and reaction heats (enthalpies), crystallinity of semi-crystalline substances, decomposition, thermal stability, oxidative stability (OIT, OOT—oxidative-induction time and oxidation onset temperature, respectively), degree of curing in resins, adhesives, etc., eutectic purity, specific heat (cp), compatibility between components, influence of aging, distribution of the molecular weight (peak form for polymers), and impact of additives, softeners or admixtures of re-granulates (for polymer materials).
Other information that can be derived from DSC measurements is tightness of binding of molecules, mechanism of binding, analysis of active material, enzyme kinetics, solution stability and molecular structure.
Existing DSC calorimeter devices include the METTLER-TOLEDO FLASH DSC 1, Nevada Nanotech Systems Self-Sensing Array device, NETZSCH® DSC 214 Polyma, and NETZSCH® DSC 204 F1 PHOENIX® as well as devices such as the PERKIN ELMER® Diamond DSC Differential Scanning calorimeter Furnace w/Chiller and DSC 4000 Standard Single-Furnace Differential Scanning calorimeter, among others in the marketplace.
Existing DSC systems, however, are often large in volume and require a large amount of sample and reference to be tested. Existing systems use a lot of material (200 μL) and are slow in operation (washing, filling, measuring). Existing system do not have high throughput and parallelization is impossible in existing systems. Such deficiencies are significant with regards to protein characterization.
It is therefore desirable to develop a device that requires lower total volume requirements and lower sample requirements than existing systems. It is further desirable to provide a device with the ability to analyze and monitor high protein concentrations (including therapeutic formulations) at higher throughput with greater flexibility and ease of use than existing technologies.
It is further desirable to provide such a device that adequately addresses the needs of bio-molecular research.
Accordingly, it is an object of the invention to provide a device that overcomes the disadvantages of the prior art.
It is an object of the invention to provide device that requires lower total volume requirements and lower sample requirements. It is another object to provide a device with the ability to analyze and monitor high protein concentrations (including therapeutic formulations) at higher throughput with greater flexibility and ease of use than existing technologies. It is another object of the invention to provide such a device that adequately addresses the needs of bio-molecular research.
In order to achieve some of the objects of the invention, the presently claimed invention requires Microelectromechanical systems (MEMS) technology. MEMS is the technology of very small devices; it merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS technology is based on fabrication technologies that can realized miniaturization, multiplicity, and microelectronics.
WO 2012/116092 A2 to Qiao Lin and Bin Wang discloses a MEMS calorimeter, fabrication techniques and uses thereof and is an example of MEMS technology for DSC systems. The contents of WO 2012/116092 A2 is hereby incorporated by reference in its entirety into this application.
“A MEMS Differential-Scanning-Calorimetric Sensor for Thermodynamic Characterization of Biomolecules” to Bin Wang and Qiao Lin in the Journal of Microelectromechanical Systems, Vol. 21, No. 5, October 2012 presented a microelectromechanical systems sensor for differential scanning calorimetry of liquid-phase biomolecular samples. The contents of this journal publication is hereby incorporated by reference in its entirety into this application.
The presently claimed invention is directed to a MEMS DSC cassette that is configured to be inserted into a DSC instrument thermal block. In principle, different blocks can be made with the ability to receive one cassette (like a standard DSC) or several (up to 12) cassettes (for multiple samples). In the configurations with several cassettes, if a user uses fewer cassettes than slots in the DSC, dummy cassettes can be used that basically just seal-off the unused positions.
The cassettes have the following advantages in that the cassettes integrate the MEMS chip and the microfluidics, provide for single or parallel use by using one or more cassettes simultaneously, can be disposable or potentially reusable, provide the interface point for a multiplexed data acquisition system, provide a convenient interface to the user, and can integrate other technologies for parallel or serial chemical analysis (absorbance, fluorescence, etc.).
The cassettes enable high measurement throughput at low volumes that make calorimetric screening of large molecular libraries possible. The cassettes use microfluidics, chip sensors, and have high sensitivity. The cassettes can include various arrays of sensors and include wafer technology in that various silicon layers and materials can be used within the cassettes. The cassettes include minimized sample consumption, low cost batch fabrication and high throughput
Furthermore, the MEMS cassettes use a chip that has a small form factor allowing the use of 100-300 times less sample than current technology, as the sample cell is approximately 1 μL in various embodiments of the invention.
Embodiments of the presently claimed invention involve providing a MEMS cassette for insertion into a DSC calorimeter comprising: a housing; and a chip mounted within the housing, the chip including: a first channel extending through the chip; a second channel extending through the chip; a first reaction area located within the first channel; a second reaction area located within the second channel; a thermopile configured to convert thermal energy from the first reaction area and the second reaction area into electrical energy, and at least one heating element, the at least one heating element configured to provide localized heat to the first and second reaction areas to generate a reaction of at least one sample located within the first reaction area and the second reaction area.
Other embodiments of the presently claimed invention involve providing a DSC calorimeter comprising: an instrument block; a temperature scanning unit; an electrical interface; and at least one MEMS cassette, wherein the at least one MEMS cassette is inserted into the instrument block and is in communication with said temperature scanning unit and said electrical interface.
Objects of the invention and its particular features and advantages will become more apparent from consideration of the following drawings and accompanying detailed description. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention is directed to one or more MEMS cassettes configured to be inserted into a DSC device as well as a DSC device that incorporates MEMS cassettes to run DSC experiments for life science research and development, specifically for bio-molecular research.
The advantages of the MEMS cassettes allow for low volume requirements, lower sample requirements and higher throughput for biological macromolecule analytics for life science research and development. The device is specifically tailored for bio-molecular research.
In certain embodiments of the invention, a MEMS cassette for insertion into a DSC calorimeter is provided comprising: a housing; and a chip mounted within the housing, the chip including: a first channel extending through the chip; a second channel extending through the chip; a first reaction area located within the first channel; a second reaction area located within the second channel; a thermopile configured to convert thermal energy from the first reaction area and the second reaction area into electrical energy, and at least one heating element, the at least one heating element configured to provide localized heat to the first and second reaction areas to generate a reaction of at least one sample located within the first reaction area and the second reaction area.
In certain embodiments, the first channel has an inlet and an outlet and the second channel has an inlet and an outlet. In certain embodiments, the first channel has more than one inlet. In certain embodiments the first channel has more than one outlet. In certain embodiments, the second channel has more than one inlet. In certain embodiments the second channel has more than one outlet.
In certain embodiments, the channels are microfluidic chambers or channels. In certain embodiments, the channels are thermally isolated and/or thermally insulated from one another.
In certain embodiments, the channels are configured to provide passive chaotic mixing for a solution or a sample solution flowing through the channels.
In certain embodiments, more than one sample can be provided, each of the samples being provided through each of the inlets into the first and second channels.
In certain embodiments, a sample or sample solution is inserted into the first reaction area and a reference is inserted into the second reaction area. In certain embodiments, the heat given from the sample is compared against the heat given from the reference.
In certain embodiments, the thermopile is configured to measure temperature differential between the first reaction chamber and the second reaction chamber. In certain embodiments, the thermopile is a thin, metal film thermopile. In certain embodiments, the thermopile is fabricated on a silicon substrate or a membrane, such as a parylene membrane. In certain embodiments, the thermocouple elements are formed from Au—Ni microjunctions. In certain embodiments, the thermophile is a thermoelectric sensor. In certain embodiments, the thermopile is made from Antimony-bismuth (Sb—Bi).
In certain embodiments, the at least one heating element includes four individual heating elements. In certain embodiments, two of the heating elements heat the first reaction area and two of the heating elements heat the second reaction area. In certain embodiments, at least a portion of the at least one heating elements are fabricated above or below the first and second reaction areas.
In certain embodiments, the at least one heating element includes a heating circuit, such that a fluid circuit is provided to heat the first reaction area and/or the second reaction area. In certain embodiments, the heating circuit involves using hot fluid to dissipate heat to the first reaction area and/or the second reaction area.
In certain embodiments, the at least one heating element is a heating coil. In certain embodiments, the at least one heating element acts as a heat exchanger. In certain embodiments, the at least one heating element is a microheater.
In certain embodiments, the first reaction area has a larger surface area than the first channel. In certain embodiments, the second reaction area has a larger surface than the second channel. In certain embodiments, the first reaction area has a larger volume than the first channel. In certain embodiments, the second reaction area has a larger volume than the second channel.
In certain embodiments, the first and second reactions areas are identical in volume and configuration and are arranged side by side.
In certain embodiments, the first and second reaction areas are each supported on a thin film substrate.
In certain embodiments, the thin film substrate includes a thermopile sensor located between the first and second reaction chambers and configured to measure the temperature differential between the first and second reaction chambers.
In certain embodiments, the first and second reaction areas are defined by a surrounding wall made from polydimethylsiloxane (PDMS). In certain embodiments, the thin film substrate of the chip can include a top layer made from a mixture of PDMS.
In certain embodiments, the first and second reaction areas are based on a freestanding polyimide diaphragm and surrounded by air cavities for thermal isolation. In certain embodiments, the heating elements are made of a thin-film gold resistive heater.
In certain embodiments, the first and second reaction areas have their temperatures varied at a constant rate.
In certain embodiments, a chemical dye is inserted into the first and the second reaction area, such that the fluorescence of the chemical dye is measured.
In certain embodiments, a chemical reaction occurs in the first reaction area. In certain embodiments, a chemical reaction occurs in the second reaction area.
In certain embodiments, a physical transformation or phase change occurs in the first reaction area. In certain embodiments, a physical transformation or phase change occurs in the second reaction area.
In certain embodiments, the chip is made of silicon or is a silicon wafer. In certain embodiments, the chip includes a thermal substrate bonded to a microfluidic structure.
In certain embodiments, the MEMS cassette is made of a thin film substrate.
In certain embodiments, the cassette housing is made of an outer plastic shell. In certain embodiments, the cassette housing is made of certain plastic materials and plastic polymer materials. In certain embodiments the cassette housing is resistant to heat, such that the cassette housing does not melt at high temperatures (over 350 degrees Fahrenheit).
In certain embodiments, the MEMS cassettes integrate mechanical elements, sensors, actuators, and electronics on a common silicone substrate through microfabrication technology. In certain embodiments, there are resistive temperature sensors and on-chip heaters located within the cassette.
In certain embodiments, the MEMS cassette and chip include a PDMS structure, polymide-PDMS intermediate layer, Sb—Bi thermopile, polymide diaphragm, micro-heater, and temperature sensor on a silicon substrate.
In certain embodiments, the cassette is configured to be electronically plugged into the DSC calorimeter. In certain embodiments, the cassette is directly plugged into the calorimeter and into the thermal block.
In certain embodiments, the cassette is in electrical connection with the DSC calorimeter. In certain embodiments, the cassette is scanned by the DSC calorimeter and DSC reactions occur within the cassette.
In certain embodiments, the cassette is disposable. In certain embodiments, the cassette is reusable and can be sterilized and cleaned.
In certain embodiments, the cassette housing comprises four channels. In certain embodiments, the four channels of the cassette are each in separate communication with a first inlet, second inlet, first outlet and second outlet in the MEMS chip, so that the four channels can transfer fluid into the first inlet and the second inlet and out of the first outlet and the second outlet.
In certain embodiments, the cassette includes a thermal interface, the thermal interface connected to the thermopile, so that the thermal interface measures the amount of electrical energy generated by thermopile. In certain embodiments, the thermal interface includes a sensor or sensing element.
In certain embodiments, the cassette housing has tapered edges at its distal end. In certain embodiments, the cassette housing is substantially rectangular. In certain embodiments, the cassette housing is cylindrical. In certain embodiments, the cassette housing has the shape of an SD card.
In certain embodiments, the cassette housing is substantially rectangular and has a length of 11.0 mm to 32.0 mm and a width of 20.0 mm to 24.00 mm.
Other objects of the invention are achieved by providing a DSC calorimeter comprising: an instrument block; a temperature scanning unit; an electrical interface; and at least one MEMS cassette, wherein the at least one MEMS cassette is inserted into the instrument block and is in communication with said temperature scanning unit and said electrical interface.
In certain embodiments, the DSC calorimeter includes at least two MEMS cassettes.
In certain embodiments, the at least two MEMS cassettes have a structure as set forth above.
In certain embodiments, the instrument block includes six ports, wherein each of the six ports is configured to receive at least one MEMS cassette. In certain embodiments, six MEMS cassettes are provided to correspond to the six ports in the instrument block.
In certain embodiments, the instrument block includes twelve ports, wherein each of the twelve ports is configured to receive at least one MEMS cassette. In certain embodiments, twelve MEMS cassettes are provided to correspond to the twelve ports in the instrument block.
In certain embodiments, the DSC calorimeter includes dummy cassettes, the dummy cassettes configured to be inserted into each of the ports in the DSC calorimeter.
In certain embodiments, the dummy cassettes are inserted into ports that are unoccupied by said MEMS cassettes.
In certain embodiments, the DSC calorimeter includes thermal control unit hardware. In certain embodiments, the DSC calorimeter includes instrument control communications and data collection electronics and firmware design and software.
In certain embodiments, the DSC calorimeter includes a user interface and data processing algorithms.
Referring to
In certain embodiments, the left chip area 118 and right chip area 115 is a thin film substrate.
Also shown in
Referring to
The DSC calorimeter 500 is able to receive MEMS cassettes 100 or 400 and/or dummy cassettes in the ports or slots. The DSC calorimeter 500 is able to conduct experiments on the MEMS cassettes located within the slots.
While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation and that various changes and modifications in form and details may be made thereto, and the scope of the appended claims should be construed as broadly as the prior art will permit.
The description of the invention is merely exemplary in nature, and thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
