2017 Fiscal Year Annual Research Report
A self-powered microneedle patch for glucose monitoring and closed-loop insulin delivery
| Project/Area Number |
17J02462
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| Research Institution | The University of Tokyo |
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Principal Investigator |
LIU LIMING 東京大学, 工学系研究科, 特別研究員(DC1)
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| Project Period (FY) |
2017-04-26 – 2020-03-31
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| Keywords | microneedles / glucose sensor / thermoelectric / quantum dots / lead sulfide / ligands / solvents |
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| Outline of Annual Research Achievements |
Porous microneedles’ modification
We found that it is very easy to coat carbon nanotube on the surface of porous microneedles. Glucose oxidase could be easily fixed on the surface of carbon nanotube coated microneedles with Nation polymer, which is biocompatible enough for skin insertion. The microneedle based glucose sensor is working very well with a maximum sensitivity up to 8 mM of glucose concentration.
Thermoelectric devices
Thermoelectric devices, which could generate electricity based on the temperature difference between human body temperature and environmental temperature, could be very suitable as an additional power generation part for our device. In order to improve the power generating efficiency, we implied leda sulfide (PbS) quantum dots (QDs) as the thermoelectric material, which have extremely low thermo-conductivity. However, its electrical conductivity is very low, which limits its application for thermoelectric devices. Here we demonstrate ligand thiophene-2,5-dicarboxylic acid, which could improve the conductivity of the QD film.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
With previous plan, we could finish the microneedle glucose sensor very quickly and achieved its sensitivity up to 8 mM, which is good enough for measuring diabetes' blood glucose concentration. However, we found that power generated by the microneedle sensor is 14.33 μW/cm2, which is not enough for supporting some built-in circuit and drug delivery. Then we decide to use thermoelectric material as an additional power generator. The material we use is lead sulfide (PbS) quantum dots (QDs), which is a very promising thermoelectric materia. During the conductivity optimization of PbS QDs, we found thiophene based ligand could give PbS QDs the highest hole mobility in the world, which is a record in PbS QD transistor.
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| Strategy for Future Research Activity |
As we found the power generated by the microneedle is not enough for the drug delivery and built-in circuit. We implied an additional power generator based on thermoelectric material PbS QDs. In order to improve the conductivity of PbS QD film, we decide to try the other method below for the next two years.
1 Molecular doping (oxidant or reductant) for PbS QDs
2 Heteroatom (Co, Ag, Gd) doping for PbS QDs
3 Liquid air assembly of large and no crack PbS QD film
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