# A Comprehensive Review of In-Body Biomedical Antennas: Design, Challenges and Applications
## 5 In-Body Antenna Applications
### Pharmacology and Optogenetics  
In Ref. [111], an injectable IBBD is presented for pharmacology and optogenetics applications, as shown in Figure 27. Pharmacology and optogenetics are widely used in neuroscience research to study the central and peripheral nervous systems. This IBBD includes a spiral antenna of approximately 5 mm in diameter, operating at a 13.56 MHz frequency. The spiral antenna is fabricated on a flexible sheet of copper clad polyimide. Tables 1-3 summarize the different types of in-body antennas for implantable, in-gestible and injectable IBBD applications, respectively, discussed in this section, highlighting their structure (type and substrate) and key performance parameters (size, gain, \(-10\) dB bandwidth and SAR). Figure 27: Wireless, battery-free, injectable microsystems for programmable pharmacology and optogenetics applications [111]. Reproduced with permission from an open-access article from _PNAS-Biological Sciences_ (CC-BY). Figure 26: Cell rover with wire antenna inserted into the cell membrane [110]. Reproduced with permission from an open-access article from _Nature Communications_ (CC-BY). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Antema** & **Ref. Application** & **Frequency** & **Size (mm \(\cdot\) cm \(\cdot\) mm)** & **Substrate/Material** & **Cain (dB)** & **Bandwidth** & **SAR\({}_{\text{log}}\) mWg** \\ \hline \multirow{8}{*}{Planar} & [90], Pacemaker & 402.5 GHz & 30.5 \(\times\) 21.02 \(\times\) 6.4 & FR4-\(\epsilon\), \(\epsilon\) = 47, tan \(\delta\) = 0.025 & - & 33.5\% & - \\ \cline{2-8}  & [25], Pacemaker & 2.4 to 2.48 GHz & 3 \(\times\) 3 \(\times\) 0.5 & Roggs 301.0 \(\times\) 10.2 & -24.9 & 22\% & 147.7 \\  & [25], Pacemaker & 2.4 to 2.48 GHz & 3 \(\times\) 3 \(\times\) 0.5 & Im \(\delta\) = 0.0023 & -24.9 & 22\% & 147.7 \\  & [92], Brain implant & 2.4 GHz & 10 \(\times\) 10 \(\times\) 1.5 & Taccom RK-S5.6, \(\pm\) 3.5, & -20.75 & 14.9\% & 0.3 \\  & [93], Brain implant & 2.4 / 48 GHz & 10 \(\times\) 87 \(\times\) 0.76 & Roggs 101.3 \(\times\) 10.2 & - & 69 \\ \cline{2-8}  & [93], Intracranial pressure & 915 MHz & 8 \(\times\) 6 \(\times\) 0.5 & Roggs 601.0 \(\times\) 10.2 & -28.5 & 9.84\% & 2000 \\  & [94], Intracranial pressure & 2.65 GHz & 8 \(\times \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Antenna** & **Ref. Application** & **Frequency** & **Size (mm \(\times\) mm \(\times\) mm)** & **Substrate/Material** & **Gain (dB)** & **Bandwidth** & **SAR\({}_{\text{log}}\) mW/kg** \\ \hline Planar & [104], CE & 433 MHz & 28 \(\times\) 12 \(\times\) 0.035 & Polyimide, \(\epsilon_{s}\) = 3.5, tan \(\delta\) = 0.0027 & \(-\)39 dB & - & - \\ \hline \multirow{3}{*}{Wire} & [105], CE & 2.4 GHz & Dia = 6.6 mm, Length = 8.85 mm & PEC wire, 0.4 mm thick & \(-\)19.83 & 12\% & \\ \cline{2-8}  & [61], CE & 1 MHz & Dia = 8.9 mm, Thick = 4.8 mm & Copper wire, 0.2 mm thick & 0.7\% PTE & - & 66 \\ \hline \multirow{3}{*}{Conformal} & [106], CE & 402 MHz, 433 MHz, 915 MHz & \multirow{3}{*}{12 \(\times\) 6 \(\times\) 17} & Kapton substrate, \(\epsilon_{s}\) = 3.5, \(-\)32.5, \(-\)30.4, \(-\)17.9 & - & - \\  & & 915 MHz & 2.45 GHz & \multirow{3}{*}{12 \(\times\) 6 \(\times\) 17} & \multirow{3}{*}{Kapton substrate, \(\epsilon_{s}\) = 3.5, \(-\)30.4, \(-\)17.9} & \multirow{3}{*}{-} & \multirow{3}{*}{-} \\  & & 915 MHz & & & & & \\ \cline{2-8}  & [107], CE & 915 MHz & 32 \(\times\) 5.8 \(\times\) 0.15 & Polyimide, \(\epsilon_{s}\) = 35, tan \(\delta\) = 0.008 & \(-\)21 & 8.9\% & \\ \hline \multirow{2}{*}{Slot} & [108], CE & 915 MHz & 7 \(\times\) 7 \(\times\) 0.675 & Silicon substrate, \(\epsilon_{s}\) = 11.9 & \multirow{2}{*}{\(-\)35.5 dB} & \multirow{2}{*}{32.8\%} & \multirow{2}{*}{
\begin{tabular}{c} 8 mW/kg for 1 \\ of tissue \\ \end{tabular} } \\ \cline{2-8}  & MIMO & [109], CE & 2.45 GHz & 5 \(\times\) 4.2 \(\times\) 0.12 & Rogers RO 3010, \(\epsilon_{s}\) = 10.2, & \multirow{2}{*}{\(-\)20.6} & \multirow{2}{*}{25\%} & \multirow{2}{*}{2000} \\  & & & & & & \\ \cline{2-8}  & & & & & & & \\ \hline \hline \end{tabular}
\end{table}