- •A ‘fundamental’ relationship of biosensor
- •Outline
- •A ‘Mendeleev table’ for biosensors
- •Strategies to beat the diffusion limit
- •Magnetic nanoparticle barcode sensor
- •Analytical solution: two limits
- •Analytical solution (ρT < ρMP)
- •Analytical solution (ρT = ρMP)
- •Analytical solution (ρT > ρMP)
- •Analytical solution: transient solution
- •Analytical solution for barcode sensor
- •A ‘Mendeleev table’ for biosensors
- •Sensor array: fragmenting sensor volume
- •Local generation/fast diffusion
- •Conclusions
Analytical solution (ρT > ρMP)
Each probe captures at most 1 target particle
∂ρ |
= D |
2 |
ρ − |
ρ |
|
|
Captured by |
∂t |
|
τ |
|
|
spherical probes |
||
|
|
|
|
|
|||
|
|
|
|
|
|
|
ρs = 0
N (t)= 4πDa0 ρt
R1 = N(t)
t = 4πDa0 ρ Per MP
R = 4πDa0 ρρMP ≡ ρ
τ
|
|
|
|
|
|
|
τ = |
1 |
|
1 |
|
|
|
4πDa |
|
ρ |
MP |
10 |
||
|
|
|||||
|
0 |
|
|
|
||
Analytical solution: transient solution
∂ρ |
= D 2 |
ρ − |
ρ |
τ ≡ |
|
1 |
1 |
|||||||||
|
|
|
|
|
||||||||||||
∂t |
|
|
4πDa0 |
|
ρMP |
|||||||||||
τ |
||||||||||||||||
|
|
|
|
|
|
|
|
|
|
r2 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
− |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||
|
|
ρ(r,t)= At−3/ |
2e−t /τ e |
|
|
|
|
|
|
|
|
|
||||
|
|
|
|
4Dt |
|
|
|
|||||||||
S (t)= |
|
∞∫ρ(r,t)4πr2dr |
|
= |
e |
−t /τ |
|
|
||||||||
|
0 |
|
|
|
|
|
|
|
|
|
||||||
∞∫ρ(r,t = 0)4πr2dr |
|
τ |
|
|
||||||||||||
0 |
Alam, Principles of Nanobiosensors, 2013 |
11 |
Analytical solution for barcode sensor
Eq. 1b
ts ρMP−1
Eq. 1a |
ts ρT−1 |
Alam, Principles of Nanobiosensors, 2013 |
12 |
A ‘Mendeleev table’ for biosensors
aM |
fM |
|
|
pM |
|
|
|
|
|
|
|
|
|
|
nM |
µM |
|
|
|
|
|
|
mM |
|||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Biobarcode sensors ‘beat’ the diffusion limit by fragmenting the space
Alam, Principles of Nanobiosensors, 2013 |
13 |
